Coolant Problems.... Arghhhhhhhh!

[sicknote]

I have posted about this before and been advised that it is probably the head gasket or water pump, however just wanted to be sure as the car isn't giving consistent symptoms.

 

It started 3 to 4 weeks ago when I noticed the coolant level light come on, when I opened the expansion cap the coolant rushed back up (under lots of pressure), this happened several times over a week or so. I was then advised that it might be a small leak on the head gasket and Kseal would cure it, so this was tried.

 

Two days after the car was taken on a run and all was well until the heaters suddenly went cold, after lots of pipe squeezing and pressure release the heaters were o.k so we went home (at no point did the car overheat). I spoke to a mechanic and they advised that the thermostat should be checked as the pipes to the rad and the rad was cold, so the stat was removed and left out to see if this rectified the problem.

 

Over the past two weeks the car had been running cooler and the heaters have been intermittent hot and cold (would usually loose heat on a run). Last week we took the car for a run and it overheated (the first time) after 80 miles of 70 mph driving. The heaters were stone cold and the expansion tank was full to the top of coollant (would point to air/blockage in system).

 

I have bled the system and it has been o.k on short runs for the past week, however today we took it for a 20 mile run, when we got to our destination the heaters were cold and the top and bottom pipes on the rad were solid. I waited for it to cool and released the pressure in the expansion tank, then on the same run home I took and detour and ran it for another 10 miles or so to see what happened. The coolant level had dropped (between min and max but no sign of coolant loss) and the pipes top and bottom of the rad were hot but no pressure!!!!!

 

During all this time the rear heaters have always blown cold and the pipes in and out of the rear matrix/aux heater have only been warm once (when it overheated), they don't pressurise like the front coolant pipes, the aux heater has never worked and the electric run-on pump doesn't work either.

 

I am now at a complete loss as to the problem. I am still thinking that the head gasket has gone/is going but it can't get to grips with the differences in pressure in the system and differences in heat.

 

Sorry for the long thread, I am usually quite competent when it come to vehicles and maintenance but this is really grinding me down!

[seatkid]

Get the coolant chemically tested for a head leak?

[chrispb123456]

Run on pumps primary function is to stop heat build up (hotspots) in the cylinder head.

Get your coolant chemically tested and pressure tested, at least one should be conclusive.

Also do a search on here, your problems aren't unique, there have been countless members on here beating around the bush changing all the easy stuff but not getting to the real problem.

Diesel heads can suffer badly from corrosion/erosion and warp, even cracks around the valve seats, most cases having the head skimmed (refaced) will restore the finish.

 

And please don't start a new topic for the same fault just carry on the original.

[sicknote]

Thanks again both for the replies. I have had the chemical test done and all is fine so will arrange to get it pressure tested. I am all geared up to replace the head gasket, water pump etc in one go, however I have also noticed (since it overheated) black deposits in the expansion tank (not oil), is it common for deposits to gather near the rear matrix and thus cause a blockage???, the black deposits have only appeared since the overheat and subsequent thorough bleeding of the system and I can now hear/feel the coolant passing through the rear pipes?

 

I have searched through the forum and on google and can see that this is quite a common problem, however there is no pattern with the symptoms and the car has only overheated once

[seatkid]

My next move would be replace water pump and thermostat and fix the run on pump.

 

Only if the problems persist go to head off job.

[sicknote]

Yeah I'm hoping to do the Water Pump etc over the christmas holidays so will see what happens then. I have noticed something this afternoon, the expansion cap has a lip on it to prevent it from making a flush seal with the expansion tank, however this has been flattened (I would guess by previous owner) so when the expansion cap is tightened it goes past the lip and makes a flush seal (if that makes any sense?), I would guess that this would have some effect on the pressure in the system as well?

[chrispb123456]

The chemical test is only drawing of air from the bottle while stationary, it's a possibility your not producing enough gas at this time so the test can be inconclusive we know the problem manifests itself when engine hot and is under load this is when the gas will be present

[sicknote]

Just one last question regarding the pressure in the system, if all of the pipes are pressurised surely this would also apply to the coolant pipes at the rear??? The reason I ask is that after a run today the system is running hot and the pipes solid, however the pipes in and around the aux. heater are cold and soft, when they are squeezed you can hear water 'sloshing' in them, the metal sections are also cold. I know that the electric pump isn't running and this is to aid circulation to the rear heater but surely the water pump should be able to provide enough circulation to reach the rear of the car.

 

So this would now lead me to think that there could be some sort of blockage or the water pump is slipping?

[chrispb123456]

The engine water pump gives a minimal circulation to the rear heater on a car that's not having circulation problems.

 

With the electric pump not working and with no other problems the rear heater would blow from hot to cold through lack of circulation.

I agree the engine water pump should be able to manage this but in practice it doesn't.

[richj]

I had exactly the same problems after I drained & refilled coolant, it took many hours of trying to bleed the system before it was fixed, turns out the aux heater at the rear is a bugger for air locks; get the front end of the car up in the air, run engine till hot with all the heaters blasting out hot, then allow to cool right down & top up. Repeat this again several times also get a new electric pump.