Overheating still..

cheet22 · Mar 17, 2012

Im back here after my rangey ws taken off the road due to overheating and suspected head gasket.

Its taken a while due to weather outside and work, but last week i finished the head gasket job, inc new water pump, thermostat, rockers. Intrestingly, there was no obvious signs of major gasket failure (no steam cleaned pistons) or any signs i could see of a slipped liner.

Anyway, she fired up first time and has been running great for a week. I fitted new track rod and drag link too this week so i could pass mot.

So, all been fine for a week, but really only driven it 50 or so miles. Needle dead on half way.

Then this morning i checked water level before going for wheel alignment. Coolant level was higher than when cold and opening cap there was a lot of pressure. I managed to slowly open it however. Car started and seemed ok again, coolant dropped after a few mins.

At wheel alignment place they left her engine running and after about 15mins coolant started pouring out of overflow pipe. Switched off as it was in the red.

Let it cool, added water slowly with cap off and running, and spewed out quickly.

Called rac, 2hrs later car was cold and he filled up again. Did a pressure test and held pressure fine for 15 or more mins. Started engine let it warm up with cap off topping up, and all fine. Drove 15 miles home and no probs. seems fine again now!

All hoses hot and flow back to tank from rad is fine.

The rac guy can only suggest the expansion tank cap, perhaps not releasing pressure when needed. Worth a shot for small cost of course

But anyone got any other ideas? Deffo seems to be getting too much pressure and so perhaps air then pushing water out? Can this happen?

dogsbody · Mar 17, 2012

Your head's cracked.

Mind you it sound's like your car's not too well either.

cheet22 · Mar 17, 2012

I had both heads pressure tested, new valves and skimmed, so hope not! (should have said this sorry) its. 4.6 too, 95

Datatek · Mar 17, 2012

Airlock when refilling.

dogsbody · Mar 17, 2012

Sorry mate but you've described a hairline crack somewhere that only opens with heat.
You could have a cracked block but if I had to put 10p on it I'd go for a head.

rangey123 · Mar 17, 2012

could be an air lock in cooling system,try bleeding it again

cheet22 · Mar 17, 2012

Quick new info - ran it up the road a couple of miles, then let it idle for ten mins. No problems.

Went back on road and twice over a couple miles the temp gauge just dropped from normal to zero (ie no temp) just for a second, maybe 2 max

Now sitting ok again

Would an airlock do that? Sounds possible if no water was passing the gauge for a second?

jt_armstrong · Mar 17, 2012

So it sounds like it is OK when you are driving and she overheats when stood still and idling. I would check your viscous fan to start with as it looks like airflow at idle is restricted. Also worth checking the radiator for hot / cold spots.
If these check out OK and you feel confident that it drives OK then take it for a good run, let it cool and see if you have used any coolant. If you have - begin to fear the worst. You could try pulling the plugs out and looking for one that is steamed cleaned.

cheet22 · Mar 17, 2012

Well certainly today that was the case.

But to be honest ive had her idling for long periods over last week in a bid to check all is well after head hasket job.

I have a feeling if i let her idle here she will happily for ages. It think its when she hits the road, pressure rises and although still fine, when idling after that she goes boom with the coolant.

Hence thinking rad cap not opening to let some pressurized air out?

I certainly did not lose any coolant over the last week of 50 miles or so.

dougdotcom · Mar 17, 2012

Have you any thoughts on a blocked rad? theses can hold a lot of crap in them sometimes weighing twice that of a new radiator some one has suggested to you to look for cold spots on the radiator where none or very little water is flowing fast enough causing a pressure build up. if its the original radiator then that's 17 yrs. of muck.

cheet22 · Mar 17, 2012

Yes thanks,

First on the to do list tomorrow

Man i am so desperate to sort this, ive only joined the elite p38 club last sept since when ive only driven the darn thing for about 3 weeks before stripping her down!

Im praying this is a rad, fan, cap, airlock issue. Any or all of them are better than taking the heads off again!

cheet22 · Mar 17, 2012

Actually something else to note

When running earlier with cap off, the pipe from rad to tank was at best tiny trickles into tank but also bubbles, certainly never a flow of water

The pipe i replaced so is deffo clear.

Should water flow from this or merely drip on occasion? This was when hot too.

jt_armstrong · Mar 17, 2012

We don't hear of many V8's surviving an overheating event. Block, gaskets or heads would be lucky to survive. This might sound rather defeatest however if the rest of your car is in good nick a new block with top hat liners will give you peace of mind for years and years. Not even as expensive as you might think especially if you can do the strip down and rebuild yourself. Probably no more than half a dozen tanks of fuel.
I'm not suggesting that the problem is this severe but I just wanted to you to undstand that its not the end of the world and could in the longer term give you a much better and more reliable P38 experience.

Druim · Mar 17, 2012

cheet22 said:
Actually something else to note

When running earlier with cap off, the pipe from rad to tank was at best tiny trickles into tank but also bubbles, certainly never a flow of water

The pipe i replaced so is deffo clear.

Should water flow from this or merely drip on occasion? This was when hot too.

You have airlocks.
Should flow with no bubbles, did you forget to take the hose off the radiator when refilling with coolant? - connect only when coolant starts flowing out radiator to avoid airlocks, and make sure the hose is clear by blowing in it first to help/ease the air out of rad when connected.

cheet22 · Mar 18, 2012

All, thanks for the help so far, update this morning

Before car started, coolant at right level, top hose normal, not collapsed or solid etc so all well to start. Absolutely no sign of oil in water or vice versa. No smell of exhust gases either.

Took small radiator to tank hose off, some air came out, not a lot, but some, then dribbles of water.

Ran her with that hose off, and cap off for 5 mins. Water continued to dribble from radiator overflow. No white smoke beyond first minute (its frosty here today)

Put hose on, cap on and went for s spin. Risked it all and went about 20 miles round trip. Got back and

1. Coolant level is up to bottom of cap, so poss ready to start pushing out!
2. Top hose solid, well, little movement but very hard
3. Looking from front of car, right 3rd side of rad pretty hot, left side cold. Middle more cold than hot. This is same top to bottom across rad.

So there is deffo too much pressure.

I guess i should check plugs when cools down a bit see if any cleaned. If they all ok, im tending towards a new cap at least. But should rad be hot all over, and should that overflow run rather than dribble? Would a duff rad cause excess pressure like this?

Druim · Mar 18, 2012

When you run the engine without hose & cap rev up sharply a couple of times to get out locked in air.
Maybe drain off a bit and refill slowly with engine running rev up now & then.
Can be a bit tricky but done slowly i managed first time so have many others.
Well you may have other issues im not experienced enough to comment so won't but common sense goes a long way.
Rave a big help too.

jt_armstrong · Mar 18, 2012

cheet22 said:
All, thanks for the help so far, update this morning

Before car started, coolant at right level, top hose normal, not collapsed or solid etc so all well to start. Absolutely no sign of oil in water or vice versa. No smell of exhust gases either.

Took small radiator to tank hose off, some air came out, not a lot, but some, then dribbles of water.

Ran her with that hose off, and cap off for 5 mins. Water continued to dribble from radiator overflow. No white smoke beyond first minute (its frosty here today)

Put hose on, cap on and went for s spin. Risked it all and went about 20 miles round trip. Got back and

1. Coolant level is up to bottom of cap, so poss ready to start pushing out!
2. Top hose solid, well, little movement but very hard
3. Looking from front of car, right 3rd side of rad pretty hot, left side cold. Middle more cold than hot. This is same top to bottom across rad.

So there is deffo too much pressure.

I guess i should check plugs when cools down a bit see if any cleaned. If they all ok, im tending towards a new cap at least. But should rad be hot all over, and should that overflow run rather than dribble? Would a duff rad cause excess pressure like this?

There is no point in second guessing something that costs nothing to do. Take the radiator out and flush it properly from both ends. Try to get as much crud out of as possible. As mentioned previously there could be 17 years worth of crap in there. Once you are happy it is cleaned out replace it in the car and refil with coolant slowly and with engine running at 1500 rpm. Remember to do the same trick with the top pipe.

Datatek · Mar 18, 2012

cheet22 said:
All, thanks for the help so far, update this morning

Before car started, coolant at right level, top hose normal, not collapsed or solid etc so all well to start. Absolutely no sign of oil in water or vice versa. No smell of exhust gases either.

Took small radiator to tank hose off, some air came out, not a lot, but some, then dribbles of water.

Ran her with that hose off, and cap off for 5 mins. Water continued to dribble from radiator overflow. No white smoke beyond first minute (its frosty here today)

Put hose on, cap on and went for s spin. Risked it all and went about 20 miles round trip. Got back and

1. Coolant level is up to bottom of cap, so poss ready to start pushing out!
2. Top hose solid, well, little movement but very hard
3. Looking from front of car, right 3rd side of rad pretty hot, left side cold. Middle more cold than hot. This is same top to bottom across rad.

So there is deffo too much pressure.

I guess i should check plugs when cools down a bit see if any cleaned. If they all ok, im tending towards a new cap at least. But should rad be hot all over, and should that overflow run rather than dribble? Would a duff rad cause excess pressure like this?

If the rad is not evenly hot all over it's likely it's partially blocked

elsie · Mar 18, 2012

air lock , more likely crack in one of the heads , pressure testing is usually done at room temp so crack would'nt have show up .

gfromleeds · Mar 18, 2012

if the rads not at an even temp all over then its blocked! might not be the cause be it certainly not helping
mine used to overheat when towing changed the rad/thermostat/cap and waterpump! and always sits bang in the middle now! no matter what im pulling (even if i boot it up garrowby hill (a f~'king steep hill messuring 2 miles) pulling a 1600kg caravan)

Overheating still..

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