Overheating 1.8 petrol at high revs

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HappyChap

New Member
Posts
8
Location
London
Hi everyone, first post and sorry to say it's a problem. I searched previous posts and could not find the same situation as mine.

I recently bought a 1.8 petrol 2001 Xreg with 32k on the clock (I am a fool I know).

Had it serviced at LR including timing belt. Following the advice here I also had the inline remote thermostat (colour grey), new coolant header tank and cap fitted.

Mainly drive in town. On my first trip on the motorway at about 3000rpm/60mph I noticed the temperature guage rose right up to the red line. I reduced revs/speed and it went back to normal. Increased speed again and same thing happened so not a one off. Tried it again this time I turned heater to hot and turned blower fan to max (no. 4) but this time temp remained at normal even at 4000+ rpm. Turned heater/fan off and guage quickly went up to red line again.

Took it back to LR who thought radiator was blocked so fitted new one. Went back on motorway and problem recurred but at higher revs, I'd say about 3500rpm/70mph. Heater and fan on again reduces temp to normal.

Coolant and oil are clear, no mayo/sludge, not losing any coolant so I don't think it is hgf (not yet anyway!). Rad fan comes on o'k, in fact quite often even after short trips. Felt top of rad while engine running and it does get hot. Otherwise drives well, no loss of power.

Any ideas as to the cause and a solution?

Regards.
 
Thanks for the quick replies.

I thought if I had hgf I would be losing coolant or have mayo in oil or coolant? But yes I am worried the overheating is a prelude to hgf.

Don't often do lunatic things I live to regret but I might have by buying a freebie!

Still, I would like to eliminate any other reasons that may be causing the prob. Could it be something else?
 
My money is on your water pump being dodgey. Either that or the new PRT is faulty, it does happen but very rarely according to MG Rover forums

Did the LR dealer remove the old stat and replace with a blanked stat ring before fitting the PRT stat?

The blanked stat ring should be on the service record, dont have part number but its only a few ££
 
Northern Irelander said:
My money is on your water pump being dodgey. Either that or the new PRT is faulty, it does happen but very rarely according to MG Rover forums

Did the LR dealer remove the old stat and replace with a blanked stat ring before fitting the PRT stat?

The blanked stat ring should be on the service record, dont have part number but its only a few ££
Click to expand...

Hi NI,

Thank you for your suggestions. I will get the water pump checked.

I have a call out to the LR mechanic about the old stat and blanked stat ring to find out, will post back.

The thing that bugs me is why turning on the heat/blower reduces the temp to normal so I am hoping it is a cooling system fault rather than something more serious. Wishful thinking perhaps.

Since owning the freebie I have spent more time looking under the bonnet checking fluids, looking at gauges, searching forums, visiting garages, spending money than in my previous 30 yrs of motoring. I have never had so much fun!
 
HappyChap said:
The thing that bugs me is why turning on the heat/blower reduces the temp to normal so I am hoping it is a cooling system fault rather than something more serious. Wishful thinking perhaps.
Click to expand...

If your engine is overheating you can release some of the heat by running it through the heater matrix/system and out into the air in the cabin. This is typical of any overheating car and (unfortunately) not any indication of the cause.

Cheers

Rog
 
Did you get an answer?

I wouldnt trust the garage who did the work, I mean if they replaced the rad and the problem still exists, then they didnt sort it in the first place.

You could go back and shout a lot, but then will they oblige?

Changing the stat is easy, we'll take you through it if you are stuck
 
rriggs said:
If your engine is overheating you can release some of the heat by running it through the heater matrix/system and out into the air in the cabin. This is typical of any overheating car and (unfortunately) not any indication of the cause.

Cheers

Rog
Click to expand...

Thanks for the info.

I suppose what I am getting at is I am surprised turning on the heat/blower "cures" the overheating but agree it does not explain the cause. That is what makes me think it is a cooling system fault rather than something else (I could be very wrong!). If diverting hot coolant to the heater matrix keeps the temp normal why can't the coolant system do it's job by letting more coolant into the radiator?

I am not sure how the coolant system works, can anyone please point me in the direction/link to a diagram of it? I am also wondering at what point does the rad fan turn on/off, e.g. over a certain temp or when it knows there is coolant in the rad?

Cheers.
 
Northern Irelander said:
Did you get an answer?

I wouldnt trust the garage who did the work, I mean if they replaced the rad and the problem still exists, then they didnt sort it in the first place.

You could go back and shout a lot, but then will they oblige?

Changing the stat is easy, we'll take you through it if you are stuck
Click to expand...

Hi NI,

Thanks for your help.

Spoke with the mechanic and he confirmed the old thermostat was removed and new blanking plate fitted.

I accept the new rad now looks unnecessary (although a very slight improvement). The rad part cost £170.

The mechanic thinks it may be a faulty thermostat (the new remote one) and I will get him to check the water pump as well.

I can’t get it back in until next week, I will report back with findings.

For what it is worth I tried a cheap fix using redline water wetter but no improvement.

The other thing I noticed was after going on a run and whilst stationary I increased the revs over 4000 and held it for about 30 seconds and the temp stayed normal. So the overheating only happens whilst driving.

In the meantime I will see if I can check if the thermo is working properly. I understand the bottom hose between new thermo and rad should heat up when the engine is hot. I am not sure how to check when the thermo is supposed to open, over 82 degrees I believe but how can that be done? Should I take it for a run to warm up then stop and increase revs and check the bottom hose?

Cheers.
 
HappyChap said:
Thanks for the info.

I suppose what I am getting at is I am surprised turning on the heat/blower "cures" the overheating but agree it does not explain the cause. That is what makes me think it is a cooling system fault rather than something else (I could be very wrong!). If diverting hot coolant to the heater matrix keeps the temp normal why can't the coolant system do it's job by letting more coolant into the radiator?

I am not sure how the coolant system works, can anyone please point me in the direction/link to a diagram of it? I am also wondering at what point does the rad fan turn on/off, e.g. over a certain temp or when it knows there is coolant in the rad?

Cheers.
Click to expand...

The heater coolant bypass is a fixed flow rate, there is no adjustment on this unless modified, or you alter fan speed

the cooling with heater on 4 is normal, the combined heat exchange coefficient of both the rad and matrix is balanced.

The standard stat is actually a restriction, its balanced on a knife edge. If you remove the stat the engine overcools.

some links below, more than what you will need to know but some good links:

http://www.landyzone.co.uk/lz/f9/hot-cold-42881.html?highlight=hot+cold

http://www.landyzone.co.uk/lz/f9/kv6-thermostat-rover-freelander-42880.html?highlight=hot+cold
 
Finally got to the bottom of this problem. The overheating was caused by the hoses to the new inline thermostat being fitted the wrong way around!

I took the car to another LR dealer for a second opinion. They did sniff (gases?) test and no problem. They initially noticed new coolant tank was damaged/cracked and not under pressure. Changed that & cap and still overheating. Then noticed bottom hose cold and discovered hoses were the wrong way around. I am told the damage to coolant tank was probably caused by overheating expanding the tank.

So it turns out the new rad fitted at original garage was unnecessary. I am in discussions with them re compensation.

Since the problem was rectified I notice the fans do not come on so often, previously came on even on short trips.
 
HappyChap said:
Finally got to the bottom of this problem. The overheating was caused by the hoses to the new inline thermostat being fitted the wrong way around!

I took the car to another LR dealer for a second opinion. They did sniff (gases?) test and no problem. They initially noticed new coolant tank was damaged/cracked and not under pressure. Changed that & cap and still overheating. Then noticed bottom hose cold and discovered hoses were the wrong way around. I am told the damage to coolant tank was probably caused by overheating expanding the tank.

So it turns out the new rad fitted at original garage was unnecessary. I am in discussions with them re compensation.

Since the problem was rectified I notice the fans do not come on so often, previously came on even on short trips.
Click to expand...

So looks like I lost that bet :p

Here's the link for hose connections on the PRT:

http://www.pagetraining.com/freelander/0026.pdf



Glad its all sorted, hopefully some comeback on the new rad, bargain hard ;)
 
Northern Irelander said:
My money is on your water pump being dodgey. Either that or the new PRT is faulty, it does happen but very rarely according to MG Rover forums
Click to expand...

Yep, cheers NI, full marks for predicting the fault.

I understand the remote thermo is marked as to which hose goes to the pump but that did not happen so disappointing. An unintentional mistake but it does beg a question if others may have been fitted incorrectly.


I have come to an arrangement to have some accessories fitted for free (tba). I'll leave it at that otherwise I could end up wasting a lot of energy going around in circles. At the moment I am all garaged out.
 
HappyChap said:
Yep, cheers NI, full marks for predicting the fault.

I understand the remote thermo is marked as to which hose goes to the pump but that did not happen so disappointing. An unintentional mistake but it does beg a question if others may have been fitted incorrectly.


I have come to an arrangement to have some accessories fitted for free (tba). I'll leave it at that otherwise I could end up wasting a lot of energy going around in circles. At the moment I am all garaged out.
Click to expand...

Well honestly, I was referring to the PRT being faulty due to the mechanism, not a hash fit by some mechanic.

Good nugget of info on the PRT being marked,;) dont think anyone has posted that info on here before?

No excuse really, if your are happy with the accessories then take whatever is going. I would be inclined to barter for a free main service
 
The Mad Hat Man said:
wud yu trust them to do a service, if they cant fit a prt properly - goodies are safer, i reckon.
Click to expand...

On second thoughts, MHM is right.

Take the accessories and run! Get the black leather arm rest, if you want to be part of Mings Black Arm Rest Gang;)

You could probably do a better job servicing the car yourself.........blindfolded:cool:
 
The car was serviced in September at 32k miles incl cam belt, brake fluid, coolant, and other belts changed fan & alternator I believe they are called, I can see they are new. Also had new heavy duty wipers and new spare wheel cover. A few months before that the car was serviced privately. The previous owner did not get the book stamped but I could see oil was fresh and a new oil filter fitted.

Pottering around town I only do about 5k miles p.a. if that. Only 33k on clock now. Next service would not be due (mileage wise) for 2 years so accessories now are the way to go. I only have the basic 'S' version, no CD, air-con, alloy wheels or sunroof & a cloth interior.
 
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