explain a bit more gav whats happened?

do you have LPG?

it is lpg, single point.

it overheated christmas day but was on road at home so parked and left. wasn't a bad o/h but lost some water due to high pressure in exp. tank.had noticed high build up of gas/air/combustion gases in exp.tank

initially stripped heads off due to suspect and supposedly confirmed (by the chemical test in exp. tank) hg failure/hydrocarbons in coolant. exessive 'steam' at tailpipe. heads were cleaned uncle measured and checked heads (40 yrs exp in mechanics) and told me was fine and in his opinion were in good tack and not warped. found a little bit of evidence to suggest hg fail but nothing overly obvious or catastrophic. i would have said they had been fine and not the cause.

only one valve head was different colour to the rest. as they were intake - light brown scale of carbon. ex. dark brown to black exept one which was cleaner but still fouled in the 'usual' way just less. pistons were not washed or steam cleaned and all showed a coating of carbon. one had a patch that was cleaner but only small and would have expected a lot more obvious signs of steam cleaning.

rebuilt heads with new gaskets etc, got one of the elec plugs on wrong. sorted that and car fired up perfect but still steamy from rear. i knew it wasnt sorted as soon as i saw exhaust. warmed car up and saw water in exp tank lower and lower. i had bled and was confident no or at least very little air locks could have been in the system. the car ran beautifully as such even though i had not yet replaced the oil(glad i didn't) and filter due to a bit of water and crud getting in the engine from the work done.

let the car get up to a good temp, went to top up the water and the level returned to previous level after removing exp. tank cap.

i had switched to gas by this time but the initial warm up was on petrol as always and especially in these circumstances.

on the way back home, got about 3 ish miles and temp shot up to red light.stopped let engine cool to just above centre topped up water then knowing i was nearly at the top of a long hill i continued then the temp rose again, not to red light this time but i dropped into neutral and coasted down the hill which brought the temp back to half way and continued for around 1 mile befor temp started to rise, stopped before red light. cooled and made it home.

the situation has got no worse or better with the strip down or o/heats.
this is where i am now and plan to strip down again tomorrow and send the heads in for a full and complete pressure test skim and then i will probably reseat or even renew all valves etc. and rbuild.

i had thought about gas system pressurising the water and pushing water into the heads either past the H/G which would surely leak the other way with compression pressure or past the intake gasket and into combustion that way. i know its a long shot but the otherwise uniform condition of internals and generally good running(exept a knocking from tappets which is now cured since rebuild) of the the engine suggests no other way water is ending up in the combustion and out through the exhaust! lets face it from what i saw of the engine there are only so many ways the water can get in there. incidently the oil was clean and no evidence of contamination before work began. there is however mayo on inside of rockers at the top but not on oil cap and it wasn't white it was brown and look like condensation rather than h/g fail and there was none in the breathers or inside plenum, just a veneer of oily deposit as usual.

please post any Q's of anything i have missed out or need clarification.

cheers guys for your support at this very dark hour!!!

gav sometimes the oil goes the other way. if water gone in oil then dipstick will have specks on it. if oil gone in water then you wont see as water will sit on top of the oil. now im thinking you have a serious airlock as the pressure is building up to quick again. before you strip down again get it pressure tested when i done the 3.5sdi gaskets i had no problems after that you are acommulating.have you tried running with out thermostat? also if the heads are warped you wouldnt notice it this quick. there still is something up with the cooling system. is the viscous fan singing on song? keep checking the obvious gav. lets us know.

did you use standard headbolts? i found with mine even though the headbolts were replaced then torqued and angle tightened i still had problems,eventually after advice from the guys at v8 tuner,i replaced the head gaskets again but used arp head studs as the clamping pressure is more consistant.but i would certainly get the heads checked and pressure tested,a crack in alloy won,t show up when it,s cold only when it,s hot,so if you do strip down again i would deffo get the heads checked professionaly,also is your thrnostat ok,the radiator flushed through,all the coolant pipes free from blockages?
also another tip to get air out of the cooling system is park the car over night with the drivers side jacked up,as air will always go to the highest point.

new stat fitted recently as this was my first port of call when pressure was building up . also no water was coming out of the rad bleed pipe before stat change and was immediatly after stat changed for new genuine part. this i assumed was the cause of airlock/pressure build up.

there was no evidence of contamination that i could see. there was a light coating of contamination on undersides of rocker covers and underside of valley gasket but again this was not excessive and could be consistent with condensation i am told, if water and oil were mixing in the proportions that seem to be coming from the exhaust then i would have expected more evidence. maybe not as i am very unfamilar with v8's and not experienced with mechanics as i'd like to be. after talking with wifes uncle(unc from here on in) he also concurrs that you would expect more overall evidence than we have had thus far!! it seems that the engine doesn't want to give up its secrets without a fight!!!

as you say brutus with the amount of gas in the coolant i would expect a major failure. of heads or gasket. if its the lpg leaking in the coolant via vap why is water coming from exhaust. i will disconnect the lpg system and try it on petrol only.(if i disconnect the solenoids on lpg tank will this allow or stop gas flow?? i expect stop and the default sol. position to be closed but just want to check first!!)

also one thing i may have not mentioned is that under high revs in neutral or park the 'smoke' or 'steam' disappears but returns when idle!!

i'm puzzled with it and cant seem to define the problem. i don't mind the fixes but i dont want to be fixxing the wrong thing!!!

andy 0352 said:

did you use standard headbolts? i found with mine even though the headbolts were replaced then torqued and angle tightened i still had problems,eventually after advice from the guys at v8 tuner,i replaced the head gaskets again but used arp head studs as the clamping pressure is more consistant.but i would certainly get the heads checked and pressure tested,a crack in alloy won,t show up when it,s cold only when it,s hot,so if you do strip down again i would deffo get the heads checked professionaly,also is your thrnostat ok,the radiator flushed through,all the coolant pipes free from blockages?
also another tip to get air out of the cooling system is park the car over night with the drivers side jacked up,as air will always go to the highest point.

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it doen't seem like air lock as the system heats the cab etc. it just gasses up as soon as the lid is on, air bubbles in a regular pattern through the exp. tank. also there is no gush of air or sudden bubble up as you would expect with an airlock. the rythem of the air in the exp tank seems to follow consistently and stops when engine off. it seems or at least to me to be coming from the cylinders hence the total conviction to it bieng heads or gaskets!!! thats why i'm puzzled. i'm not discounting any theory as i am so far from the fault anything is possible!!

i'm gonna take off the exhausts just after the manifolds to see if its a particular bank and so dispell a theory of it getting into the intake someway and the lpg system pressurizing as in two seperate problems or lpg causing coolant leak into intake due to presuure in coolant system. it does get up to quite a high pressure and i imagine could force water somewhere it might not normally go!!

the lpg vap did freeze a few weeks ago but i put this down to coolant level, round about the same time as i first noticed the problems. could this be the cause of pressure if the vap internals have gone????

i did use the standard head bolts and the standard method of tensioning. i did have a feeling that things werent tight enough even though i followed the method to the letter!!

you will have excess water in bottom of engine that needs to be burned of. that will be the smoke you are getting i would of thort.. as for lpg im noy a fan of them so cannot help you, but if it wasnt running crrectly or should i say flwoing correctly then yes i reckon you will be running hotter. as you have accounted the stat. run on fuel like you suggested and see if any difference. you obviously done the head gasket correctly as you uncle over looking the deed.

got to agree with brutus any water left in the engine system will take a few days of running around to burn it off,there will also be water in the exhaust system until it gets steamed out

as far as i know everything was done to the letter, except the elec plugs i got wrong but i sorted that. even consulted the rave cd for plug leads 4 times to make sure the thing was correct. each stage i did unc had a look and checked the next step etc. only bit he didn't check was final assembly/connecting of plug leads and injector leads but these are correct as it wouldnt run otherwise!! there doesnt seem to be a power loss although it's never pinned me into the seat i did notice a sluggishness but put this down to driving the deisel van for a couple of days and the difference in vehicles.

assuming problem is still there after each step, plan of attack tommorow is:
1, run on petrol back to unc yard about 4 ish miles.
2, strip exhausts and run to see if its a manifold in particular. (although this could be futile its worth a try)
3, disconnect water side of lpg to see if pressure is still in system(i assume chemical test of coolant would show lpg as hydrocarbons????)
4, strip and pressure test heads, obviously noting the suspect head if found in step 2
5, probably later in week/next week re assemble with another gasket kit etc and having to resqueeze all 16 bloody lifters and reseat valves and basically refurb heads.
6, check if problem remains if so torch the bastard!!!!

anything ive missed??? oh i forgot, chuck in a compression test somewhere before and after head strip/rebuild!!

andy 0352 said:

got to agree with brutus any water left in the engine system will take a few days of running around to burn it off,there will also be water in the exhaust system until it gets steamed out

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i was told this but then the pressure problem remains so immediatly dismissed it. will the manifold check above prove wothwhile in eliminating water build up in exhaust?

i could do without changing oil but if its gonna give me a fix then i will gladly flush and refill!

gav get compression done before you strip down again. only need the water system pressurised. dissconect ya gas get it pressurised then take it from there. dont strip of heads again as that not the cause of the prob. you uncle with ya @ he already said ya heads are fine. a decoke of heads will run better but wont maka any difference to the coolong system which is where we think the prob lies. report back after compression test then we help out again. chin up pal we feel for ya and we all here to help.

sorry if this has been tried but i spent over £2.5k with a suspect engine which i changed myself only to find the exact same fault after 20 miles turns out my lpg vaporizer had failed pressurising the water system if i was u i would link out the lpg vaporizer and disconnect the gas solenoid and try again

andy lets hope ya right as it sounds like under pressure all the time. i dont nothing on lpg not fan of em.

andytlman said:

sorry if this has been tried but i spent over £2.5k with a suspect engine which i changed myself only to find the exact same fault after 20 miles turns out my lpg vaporizer had failed pressurising the water system if i was u i would link out the lpg vaporizer and disconnect the gas solenoid and try again

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i read your comments on another post and this is whats making me take out the gas side of things to eliminate that.

unc hasn't a clue on gas and neither do i really apart from the obvious and logical. as with most things i have to take em apart to undertand them.

did you get any steam in the exhaust when your prob occurred?
i know its possibly in the exhaust/engine or maybe another route into pots but i would like to eliminate every possibilty before i get to the strip.

i would like it to be the vap. as this is qutie an easy fix as i want to upgrade the lpg system.

could the lpg pressure push water past gaskets in the head causing steam.

i'm sure the lpg is at around 30 or 40 psi would this be enough?

what kind of pressure is in the compression compared to lpg system?

i know the stepper motor that allows gas to the intake pulses open and shut to some degree. if the solonoids on the high pressure side were also pulsing this would explain the 'gas' bubble frequency in the exp.tank i suppose!

do you ever get the feeling that with every answer another question arises!!!

gawd i'm gonna go stir crazy at this rate!!! i might put a gas turbine engine in it, make it the fastest P38 in the world!! are G.T engines water cooled?

oh and i do appreciate all your help guys,

after reading some of my posts it sounds like i'm poo pooing yr theories, i'm not i'm trying to answer questions and get as clear as we can be to save me hassle and money, and also maybe help a few others on the way!!

once again thanks to all who are helping me here!

i'll be setting off early in morning but if anything comes to mind i will be checking forum so don't hesitate to mention it!

lpg runs at 120psi + so a minor leak could cause a problem my main problem was excess pressure in the water system and intermittently blowing water out the head tank everybody (experts ha ha) told me slipped liner so i changed the engine and found out the expensive way. I would now tackle things differently i would set each piston so each valve closed and bdc rig up an air line in the spark plug hole and pressurise each barrel and look for bubbles/pressure in water.

btw i still have my old short engine just incase!

just read that compression is around 140 - 160 psi

lets us know how you get on gav,i don,t have lpg on mine,we were debating about it,but i know nothing about lpg systems other than they can make your engine run hotter,and thats about it,but like brutus said if you can disconnect the lpg side and see how it goes on petrol,it could be something on the lpg system that is causing the problem??