corfunightmare
New Member
I'm about to remove the heads and replace the gaskets, does anyone know if there are any precautions i need to take when removing. Also do I have to use new head bolts or can I get away with using the old ones.
I recently removed both heads on my 4.6 in the rave manual it says to disconnect the steering column this is unnecessary i managed to remove the right hand manifold with out taking the column out personal i would spend a little more time diagnosing fault before pulling apart i rushed in and spent £3k on a short engine after listening to all the "experts " advice when it was actually my LPG system pressurising the coolant. If i was diagnosing the fault now i would pressurise each bore with 120 psi air line with valves shut and look for air bubbles in header tank. It took me around 8 hours to remove both heads i would def use new head bolts as they are really tight and genuine head gasket ,valley gasket, upper inlet gasket and while heads off valve stem oil seals ,water pump gasket and possibly timing cover gasket
^^^^ do that!!
Good advice there....i've rebuilt countless engines from lawnmowers to v6 race engines. A mates timing belt went on a car worth about 100 quid and he asked me to sort it cheap. It needed 2 new valves and to save money the only parts i replaced was the HG and the 2 bent valves....big mistake. It ran ok for a bit but because i used the same bolts and basically didn't replace all the things i should have it ended up blowing the HG about 600 miles later. That was a 4 cylinder astra......don't risk it on a V8. renew everything.
Good luck
Good advice there....i've rebuilt countless engines from lawnmowers to v6 race engines. A mates timing belt went on a car worth about 100 quid and he asked me to sort it cheap. It needed 2 new valves and to save money the only parts i replaced was the HG and the 2 bent valves....big mistake. It ran ok for a bit but because i used the same bolts and basically didn't replace all the things i should have it ended up blowing the HG about 600 miles later. That was a 4 cylinder astra......don't risk it on a V8. renew everything.
Good luck
As regards fitting new head bolts, (is this a poison chalice) I only change the bolts that dont ring when balanced on the finger & tapped with a spanner & this is rare. They are called stretch bolts & if they ring they still have plenty of stretch. If you have the money, by all means carry on & fit new, as for me (a Mechanic for 42 yrs. with Land Rover factory training & many others vehicle makes) I only replace what needs to be replaced on the basis of how long the component last.
Clean the bolts & lightly oil them, they should run in with your fingers on a socket, if not & they are tight run them up & down until they are loose.
The head bolts are not to tight, as the heads are aluminium just tighten them up in three stages with the correct sequence @ 20lbs. ft. then 40lbs. ft. & finally 65lbs. ft. (70lbs.ft. max) never had a problem.
If there is a problem with the engine that the cylinder head/s has had to come off, the head/s must be checked for level & if required planed level. Its no use just fitting a new gasket, replacing damaged bent valves etc. it wont last unless, you were very lucky.
Those with older engines with three rows of head bolts, tighten the centre & lower row of bolts as above, the outer row above nip them down to only 30lbs.ft. It has been shown that this row of bolts, (now removed on the later engines) were flexing the head causing the gasket to fail.
Refill with good quality antifreeze & this will last the life of the engine, yes it will!
Regards Trevor
Clean the bolts & lightly oil them, they should run in with your fingers on a socket, if not & they are tight run them up & down until they are loose.
The head bolts are not to tight, as the heads are aluminium just tighten them up in three stages with the correct sequence @ 20lbs. ft. then 40lbs. ft. & finally 65lbs. ft. (70lbs.ft. max) never had a problem.
If there is a problem with the engine that the cylinder head/s has had to come off, the head/s must be checked for level & if required planed level. Its no use just fitting a new gasket, replacing damaged bent valves etc. it wont last unless, you were very lucky.
Those with older engines with three rows of head bolts, tighten the centre & lower row of bolts as above, the outer row above nip them down to only 30lbs.ft. It has been shown that this row of bolts, (now removed on the later engines) were flexing the head causing the gasket to fail.
Refill with good quality antifreeze & this will last the life of the engine, yes it will!
Regards Trevor
For the sake of £38(which is what i paid) i personal would replace bolts when i undid the head bolts on my car with a long cracker bar with the assistance of another to steady the socket the bolts cracked twice before becoming free. Also as per RAVE CD the latest tignening sequence is 20 NM followed by 90 degrees followed by 90 degrees not sure what that works out to be in total NM.
i definitely agree with all that has been said about checking the condition of the heads tho
i definitely agree with all that has been said about checking the condition of the heads tho
Almost all of the advice you received is excellent. However, there are couple of important watchpoint unmentioned.
1. I would not ever recommend reusing head bolts..but it in your case there is no option. Land Rover, like other auto manufacturers switched to "stretch" bolts more than a decade ago. These are bolts that are designed to be used once. They stretch on installation and requiring no retorquing after 500 miles (as used to be the case with the regular bolts used many years ago).
The non-necessity of retorquing is why the manufacturers love them. They are not "better" bolts per se. They are used for the heads and the crank. If you try to use them twice, they can twist like licorice and snap like plastic, leaving you looking at a sheared bolt in your block.
Aside from that codicil..I have nothing terribly against them. However, you do NOT use the old torquing method to install them..you must use "stretch bolt torquing". That is done three stages. First torque all to 15 lbs using the correct sequence, mark them with a bit of white paint for reference and then turn them all 90 degrees using the same sequence and then finally 90 degrees again in sequence. Never turn any bolt 180 at once.
2. Always follow the torque sequencel. REMOVE the heads in reverse sequence and reinstall them using the stock torque sequence
1. I would not ever recommend reusing head bolts..but it in your case there is no option. Land Rover, like other auto manufacturers switched to "stretch" bolts more than a decade ago. These are bolts that are designed to be used once. They stretch on installation and requiring no retorquing after 500 miles (as used to be the case with the regular bolts used many years ago).
The non-necessity of retorquing is why the manufacturers love them. They are not "better" bolts per se. They are used for the heads and the crank. If you try to use them twice, they can twist like licorice and snap like plastic, leaving you looking at a sheared bolt in your block.
Aside from that codicil..I have nothing terribly against them. However, you do NOT use the old torquing method to install them..you must use "stretch bolt torquing". That is done three stages. First torque all to 15 lbs using the correct sequence, mark them with a bit of white paint for reference and then turn them all 90 degrees using the same sequence and then finally 90 degrees again in sequence. Never turn any bolt 180 at once.
2. Always follow the torque sequencel. REMOVE the heads in reverse sequence and reinstall them using the stock torque sequence
Gomog, may I ask from what “experience” you are quoting ref . stretch bolts?
(“If you try to use them twice, they can twist like liquorice and snap like plastic”
Yes I agree somewhat with that statement, if the bolt is ”knackered” & has not been checked properly by an experienced person it will snap, like any other bolt, stretch or non stretch.
Bolts that are adjacent to the exhaust manifold can fail, if an engine is allowed to persistently overheat, the elasticity of the bolt may fail leading to a gasket failure, on examination should be replaced.
Wheel nuts on trucks (HGV’s) are stretch studs, with a flat face nut & are tightened in the region of 475lbsft & it is the clamping force of the combined elasticity of the stud & the torque of the nut that holds the wheel on. Wheels are removed from trucks as a matter of course during maintenance & rarely is a stud/nut replaced unless it is damaged.
The quality steel bolt on an alloy cylinder head is only torqued to 65-70lbsft. If a bolt is examined properly it can be safely used more than once.
(Remember the chap/designer who put 3 rows of bolts on the cylinder head, everyone believed he was right, until someone came up with the 2 row head?)
If you torque all the bolts to a specified torque for that size of bolt (old school) you know, that every bolt has exactly the same clamping force. If you turn a bolt through 90deg & 90deg again there is no way you can guarantee that all the bolts are exactly at the same (clamping force) because the dial gauge you are turning with, as a human being you will never get them all the same, however with the click of a calibrated torque wrench you will.
I have discussed this with some engine re-manufactures who rebuild engines all day long & they use the torque method, why, because sometimes at their cost without a torque wrench to regulate the tightening, a bolt as damaged a cylinder head & or pulled the threads on the block, old school vers. new school. the argument will never be settled.
Do you replace all the injectors/spark plugs/glow plugs when only one has failed? do you fit dampers/tyres/springs/airbags etc. in pairs? do you change all the bulbs when one has failed? without testing, do you change your antifreeze, all the oils to soon? if the answer is yes, the manufactures are rubbing their hands in profit as you are a paid up member of the fit new brigade.
(“If you try to use them twice, they can twist like liquorice and snap like plastic”
Yes I agree somewhat with that statement, if the bolt is ”knackered” & has not been checked properly by an experienced person it will snap, like any other bolt, stretch or non stretch.
Bolts that are adjacent to the exhaust manifold can fail, if an engine is allowed to persistently overheat, the elasticity of the bolt may fail leading to a gasket failure, on examination should be replaced.
Wheel nuts on trucks (HGV’s) are stretch studs, with a flat face nut & are tightened in the region of 475lbsft & it is the clamping force of the combined elasticity of the stud & the torque of the nut that holds the wheel on. Wheels are removed from trucks as a matter of course during maintenance & rarely is a stud/nut replaced unless it is damaged.
The quality steel bolt on an alloy cylinder head is only torqued to 65-70lbsft. If a bolt is examined properly it can be safely used more than once.
(Remember the chap/designer who put 3 rows of bolts on the cylinder head, everyone believed he was right, until someone came up with the 2 row head?)
If you torque all the bolts to a specified torque for that size of bolt (old school) you know, that every bolt has exactly the same clamping force. If you turn a bolt through 90deg & 90deg again there is no way you can guarantee that all the bolts are exactly at the same (clamping force) because the dial gauge you are turning with, as a human being you will never get them all the same, however with the click of a calibrated torque wrench you will.
I have discussed this with some engine re-manufactures who rebuild engines all day long & they use the torque method, why, because sometimes at their cost without a torque wrench to regulate the tightening, a bolt as damaged a cylinder head & or pulled the threads on the block, old school vers. new school. the argument will never be settled.
Do you replace all the injectors/spark plugs/glow plugs when only one has failed? do you fit dampers/tyres/springs/airbags etc. in pairs? do you change all the bulbs when one has failed? without testing, do you change your antifreeze, all the oils to soon? if the answer is yes, the manufactures are rubbing their hands in profit as you are a paid up member of the fit new brigade.
Doobs too
New Member
I don't dispute anything you've said except the bit above. Clamp force and torque are not directly related, there is a third variable which is friction. Small variations in friction result in suprisingly large clamp load differences. The torque angle method of tightening bolts does result in a more consistant clamp load if desgined correctly.
The combination of torque and angle should be specified so that the bolt exceeds it's elastic limit (and so reaches a minimum clamp load). As it is undergoing plastic deformation it is unable to do any more work as it's tightened (which defines the upper limit of clamp load). If you look at the load / deflection curve of a bolt you'll see this region is fairly flat, which translates to the lower and upper limits of clamp load being close together.
I belive that bolts tightened in this way can be used 4-5 times (loads of disclaimers here, including ensuring the bolt has never been previously overtightened etc etc). The question I have not ever had answered satisfactorily is how do you know how many times it's been used before? Testing its ring is an interesting method.
david451
New Member
I dont always replace the head bolts, but I do measure them against a new one, if it's stretched too much, new ones, and be careful it dont bottom out coz it's stretched and even having done that it's not uncommon to break one and have to strip it all down again. It comes out ok but it's a pain in the arse.
I dont like angle torqueing it's a guess, and you are right torqueing with a setting is definately the best way. Stick a torque wrench on as you angle them and watch how mad the varience is from one to the other. far too fookin tight as well.
The last time I did a v8 there was stuff on the bolts that had to be cleaned off and replaced which stopped them siezing up in the block.
Personal experience of course. And the may times trying to clean up after those who tried to reuse them and had the result I describe.
gomog said:
You misunderstood. I did not qualify my statement. Stretch bolts should NEVER be re-used. Even if they don't snap or twist, they cannot be retorqued..they just keep streching until they snap.
Frankly, I have much skepticism why some use any type head bolts twice, but I understand that low budgets means the acceptance of unnecessary risks. However, stretch bolts are a unquestioned no-no.
I have no desire to convince you shoudl you wish not to be conviced.
However, anyone can simply google "reusing stretch bolts" and find the experience is universal. One call also try googling "reusing head bolts" for comments on reusing non-stretch bolts.
Np. Go for it.
Not really, Everyone in racing knew that one was dumb by the early 80s. (the Nick Mann era). easy enough to slack off the lower row. Of course, it took LR another 15 years to figure it out.
(sigh) We are not on the same page. You are referring to the tendency of all bolts to strech and I am referring to stretch bolts, specially fashioned elastic bolts used by auto manufacturers for the last 15 years for reasons I noted above. all_head_bolts
Simply put, they are newer bolt technology that has become part of every manufactured vehicle today. It is best to learn their strengths and weaknesses.
You are talking to remanfacturers who (hopefully) are not using the newer bolts and still order the old stuff. You can tell by asking them whether they recommedn retorquing after usage. Many people trained in the days of yore are resistant to change (me too sometimes!) and new technology. Within the context of the old style bolts they are using, I imagine the discussions are great fun. However, that type of bolt reality left the factories some time ago. Even I still prefer new ARP bolts over anything.
More than that. I change ALL my plugs regularly and now never see one fail. I change dampers in pairs to keep the suspension balanced and well-functioning. I change my tyres in pairs at least, more often all at once..so my safety and traction are not compromised. I change pads, shoes, rotors, drums in pairs )so my brakes always work). I do not re-use my motor oil, or my axle or gearbox fluids and change them regularly as well. I use clean grease, and refuse to reuse the old grease.
Works for me! I have 5 of these engines (at the moment) and they have an aggregate of 450,000 miles. The compression is even across all 5 sets of cylinders and I am proud to use any of them. I haven't been to a LR dealer in my life. No need. Do everything myself.
Should I ask how you treat yours? ;-)
Personal experience of course. And the scores of times trying to clean up after those who tried to reuse these things and had the results I describe.
gomog said:
You misunderstood. I did not qualify my statement. Stretch bolts should NEVER be re-used. Even if they don't snap or twist, they cannot be retorqued..they just keep streching until they snap.
Frankly, I have much skepticism why some use any type head bolts twice, but I understand that low budgets means the acceptance of unnecessary risks. However, stretch bolts are a unquestioned no-no.
I have no desire to convince you shoudl you wish not to be conviced.
However, anyone can simply google "reusing stretch bolts" and find the experience is universal. One call also try googling "reusing head bolts" for comments on reusing non-stretch bolts.
Np. Go for it.
Not really, Everyone in racing knew that one was dumb by the early 80s. (the Nick Mann era). easy enough to slack off the lower row. Of course, it took LR another 15 years to figure it out.
(sigh) We are not on the same page. You are referring to the tendency of all bolts to strech and I am referring to stretch bolts, specially fashioned elastic bolts used by auto manufacturers for the last 15 years for reasons I noted above. all_head_bolts
Simply put, they are newer bolt technology that has become part of every manufactured vehicle today. It is best to learn their strengths and weaknesses.
You are talking to remanfacturers who (hopefully) are not using the newer bolts and still order the old stuff. You can tell by asking them whether they recommedn retorquing after usage. Many people trained in the days of yore are resistant to change (me too sometimes!) and new technology. Within the context of the old style bolts they are using, I imagine the discussions are great fun. However, that type of bolt reality left the factories some time ago. Even I still prefer new ARP bolts over anything.
More than that. I change ALL my plugs regularly and now never see one fail. I change dampers in pairs to keep the suspension balanced and well-functioning. I change my tyres in pairs at least, more often all at once..so my safety and traction are not compromised. I change pads, shoes, rotors, drums in pairs )so my brakes always work). I do not re-use my motor oil, or my axle or gearbox fluids and change them regularly as well. I use clean grease, and refuse to reuse the old grease.
Works for me! I have 5 of these engines (at the moment) and they have an aggregate of 450,000 miles. The compression is even across all 5 sets of cylinders and I am proud to use any of them. I haven't been to a LR dealer in my life. No need. Do everything myself.
Should I ask how you treat yours? ;-)
Personal experience of course. And the scores of times trying to clean up after those who tried to reuse these things and had the results I describe.
gomog said:
You misunderstood. I did not qualify my statement. Stretch bolts should NEVER be re-used. Even if they don't snap or twist, they cannot be retorqued..they just keep streching until they snap.
Frankly, I am amazed that some use any type of head bolts twice, but I understand that low budgets forces the acceptance of greater risk. However, stretch bolts are an unquestioned no-no.
I have no desire to convince you..should you wish not to be convinced.
However, any here can simply google "reusing stretch bolts" and find the experience I describe is universal. One call also try googling "reusing head bolts" for comments on reusing non-stretch bolts.
Np. Go for it.
Not really, Everyone in racing knew that one was dumb by the early 80s. (the Nick Mann era). easy enough to slack off the lower row. Of course, it took LR another 15 years to figure it out.
(sigh) We are not on the same page. You are referring to the tendency of all bolts to stretch and I am referring to stretch bolts, specially fashioned elastic bolts used by auto manufacturers for the last 15 years for reasons I noted in another posting above. all_head_bolts
Simply put, they are newer bolt technology that has become part of every manufactured vehicle today. It is best to learn their strengths and weaknesses.
You are talking to remanfacturers who (hopefully) are not using the newer bolts and still order the old stuff. You can tell by asking them whether they recommend retorquing after 500 miles or whatever. If they say yes, they are not using stretch bolts.
Many people trained in the days of yore are resistant to change (me too sometimes!) and new technology. Within the context of the old style bolts these guys are using, I imagine the discussions are great fun. However, that type of bolt reality left the factories some time ago (though even I still prefer new ARP bolts over anything).
More than that. I change ALL my plugs regularly and never see one fail. I change dampers in pairs to keep the suspension balanced and well-functioning. I change my tyres in pairs at least, more often all at once..so my safety and traction and fun are not compromised. I change pads, shoes, rotors, drums in pairs) so my brakes always work. I do not re-use motor oil, or my axle or gearbox fluids and I change all them regularly as well. I use clean grease, refusing to reuse the old dirty stuff.
(I do wish I COULD reuse my petrol though!).
Works for me! I have 5 of these engines (at the moment) and they have an aggregate of 450,000 miles on them. The compression is even across all 5 sets of cylinders and I am proud to use any of them. I haven't been to a LR dealer in my life. No need. Do everything myself.
Should I ask how you treat your vehicles? ;-)
No need to answer.
Pikey
Dummy Ejection Facilitator..
I think he heard you the 1st time.
Sorry. I assumed his specific question to me the second time meant he didn't hear it.
Thx for your help.
I see you a fully paid up member of the fit new brigade & cannot judge the wear of component, have little or no diagnostic capabilities therefore just fit new. The motor factors rub their hands when you walk in the door. As regards my P38 it's 10 yrs old & is in very "mint" condition with plenty of tlc, not fnb.
PS Who the hell reuses old oils & grease?
More than that. I change ALL my plugs regularly and now never see one fail. I change dampers in pairs to keep the suspension balanced and well-functioning. I change my tyres in pairs at least, more often all at once..so my safety and traction are not compromised. I change pads, shoes, rotors, drums in pairs )so my brakes always work). I do not re-use my motor oil, or my axle or gearbox fluids and change them regularly as well. I use clean grease, and refuse to reuse the old grease.
Works for me! I have 5 of these engines (at the moment) and they have an aggregate of 450,000 miles. The compression is even across all 5 sets of cylinders and I am proud to use any of them. I haven't been to a LR dealer in my life. No need. Do everything myself.
Should I ask how you treat yours? ;-)[/quote]
Doobs,
With regards to “friction” that is why the threads on a nut or a bolt & the block are cleaned & lubricated to reduce the friction as much as reasonably possible.
With regards clamping force & torque, please explain your version further?
When you apply torque to a bolt/nut (torque being “ any force that causes rotation) & clamp, being two objects being secured together. Therefore to join/secure two surfaces together you would apply a specific torque to a nut/bolt to secure the said two surfaces together.
Iff you only use the angle method, how do you know at what final torque you have attained? Being that a specific bolt/nut size will only take a certain amount of stress & I have seen the results/damage by only using the angle method. Aluminium heads & blocks are delicate & require a constant & specific torque.
Have you ever seriously worked on an engine? ever, attained professional qualifications in motor vehicle mechanics? worked with qualified motor vehicle technicians & also debated the above with the newbies & the oldies? not ever resistant to change however a balance must be made between common sense & practical application from the rule book, blindly follow or interpretation?
There will always be debate & differences on the above subject,I hope you don’t pull a bolt out of the block I won’t.
As regards testing a bolt with the “ring” it makes when tapped with another metal object, this was a simple method of testing a cheap spanner against a quality spanner, the quality spanner will ring & the cheap spanner won’t, the same basic method applies to bolts (old school) yes it does work. In the metallurgic laboratory at university this test was applied & backed up by machine metal testing.
You say “I believe that bolts tightened in this way can be used 4-5 times (loads of disclaimers here” Ideally heads should never have to be removed, once yes/maybe, but 4-5 times something is seriously wrong with the person doing the repairs.
With regards to “friction” that is why the threads on a nut or a bolt & the block are cleaned & lubricated to reduce the friction as much as reasonably possible.
With regards clamping force & torque, please explain your version further?
When you apply torque to a bolt/nut (torque being “ any force that causes rotation) & clamp, being two objects being secured together. Therefore to join/secure two surfaces together you would apply a specific torque to a nut/bolt to secure the said two surfaces together.
Iff you only use the angle method, how do you know at what final torque you have attained? Being that a specific bolt/nut size will only take a certain amount of stress & I have seen the results/damage by only using the angle method. Aluminium heads & blocks are delicate & require a constant & specific torque.
Have you ever seriously worked on an engine? ever, attained professional qualifications in motor vehicle mechanics? worked with qualified motor vehicle technicians & also debated the above with the newbies & the oldies? not ever resistant to change however a balance must be made between common sense & practical application from the rule book, blindly follow or interpretation?
There will always be debate & differences on the above subject,I hope you don’t pull a bolt out of the block I won’t.
As regards testing a bolt with the “ring” it makes when tapped with another metal object, this was a simple method of testing a cheap spanner against a quality spanner, the quality spanner will ring & the cheap spanner won’t, the same basic method applies to bolts (old school) yes it does work. In the metallurgic laboratory at university this test was applied & backed up by machine metal testing.
You say “I believe that bolts tightened in this way can be used 4-5 times (loads of disclaimers here” Ideally heads should never have to be removed, once yes/maybe, but 4-5 times something is seriously wrong with the person doing the repairs.
corfunightmare
New Member
Hi Guys,
Thanks for all that very useful info really appreciate it.
However I eventually managed to source a radiator from the UK after replacing the thermostat, viscous fan etc. Replaced the Rad, pressure build up disappeared and the temperature has become normal, in fact its running cooler than i've ever known it. Considering the outside temperatures of 41 degress.
Just shows the importance of a non blocked Rad.
Thanks again boys, this site is the best for info.
Regards to all,
Andy.
Thanks for all that very useful info really appreciate it.
However I eventually managed to source a radiator from the UK after replacing the thermostat, viscous fan etc. Replaced the Rad, pressure build up disappeared and the temperature has become normal, in fact its running cooler than i've ever known it. Considering the outside temperatures of 41 degress.
Just shows the importance of a non blocked Rad.
Thanks again boys, this site is the best for info.
Regards to all,
Andy.
That was an interesting leap into the unknown!
Actually, over the last few years, I have lost confidence in new parts. So many of them fail from the box. I prefer, wherever possible, to have mine rebuilt or remachined by myself or locally.
If you wish to feel that my use of new spark plugs indicates some failing in my diagnostic ability. So be it.
If you wish to re-use head and crank bolts over and over again as I said before, do so. It is important for the community to have a least a few people who take such risks.
That is a new engine in my book, made (I believe) after the LR stretch bolt era began. My blocks are 1963 (Jetfire), 1984 (3.5), 1990 (3.5) 2000 (4.8) and a 4.6 (2004). All running well.
Do you have only the one engine? I imagine that you haven't had to do any major work on it yet. I imagine you will reuse its head and crank bolts when the time comes. Wish I could be there to hand your torque wrench.
