300TDi Head / Overheat Problem

[RichardAllen]

I had a brief overheat which may have been due to some coolant freezing in the recent weather and blocking / jamming the thermostat. I had a feeling the coolant was a bit under-spec.

After I stopped it cleared very quickly and all returned to normal. Keeping an eye on the coolant level I noticed that it started to drop, so I kept it topped up over a few days, but noticed a lot more steam on starting which then stopped when the engine warmed up. Suspecting a small head gasket leak, I ordered a new one. However, on one occasion the engine faltered on starting as if there was a cylinder full of water. Worrying.

When I took the head off the bolts were about equal torque, no really stiff ones. There was no obvious damage to the old gasket, the head seems straight (but I have not put a proper straightedge on it yet), and there were no obvious cracks. The head is a relatively new Turner one (<30,000 miles) so where was all the water coming from ?

I put a new head gasket on and ran it up briefly yesterday. However, it was getting dark. This morning, I could not get the engine to turn over. I pulled the injectors and #4 injector was clearly wet. When i turned the engine over, water sprayed out of #4.

This afternoon I took the head off and again no obvious damage, though #4 was full of water. The only thing I can think of is that the head did not seat on the dowels properly.

So I plan to refit the head tomorrow making sure the dowels fit properly.

However, might there be some not-so-obvious frost damage some where ?

All ideas very welcome.

Regards

Richard

[davyd8899]

if you tourqed the the head down before running it up it would of sat correctly, if it wasnt sitting on the dowels then you would of noticed an obvious gap between the head and engine block.

if no. 4 is filling with water there i would imagine the head has an internal crack somewhere thats not obvious to the naked eye.

its worth getting the head checked/ machined for straightness, however it sounds to me like an internal head problem that cannot be seen. a pressure test will pick up on this, though when you have pulled the head off fill the inlet/outlet ports with diesel/cerrosine or some other suitable fluid. this may give a pointer as to where the leak is coming from, again though this isnt fool proof as it may not show up under normal circumstances but would do under pressure.

ice damage is a killer, i know how it feels so can really sympathise with you, if this was the cause, also if it overheated, again this is enough to crack the head.

did the water bubble up through the header tank with the engine running? also if the cylinders are pressurising the coolant system then this will send the temp guage skywards even though it may not be overheating as such.

hope all this helps and good luck i had a nightmare tith my 300tdi until the problem was finally diagnosed. i had a crack down 1 of the ports not visable to the eyes, and it was displaying all the symptoms you have described-a new head and all was well again.

hope this helps.

[muddy]

I'd get the head pressure tested and skimmed, i have done a def 200 and disco 300 in the last fortnight, both were 8 thou out, one chuffing out the back of the head and one chuffing into the pushrod tube, neither overheated.

I presume you used a decent gasket?

Will.

[Tony Edward]

Todo list in order:-

1. Pressure Test the Head.

2. If OK them get head skimmed to ensure correct mating to block

3. If not OK then obtain new head and lap and fit valves and springs

3. Obtain Multi Layer Steel (MLS) head gasket with correct number of holes (thickness indicators)

4. Obtain new locating dowels and fit to block

5. Clean out all head bolt holes and run appropriate bottoming tap into each.

6. Refit head and ensure that the torque settings and the subsequent angular tightening of all head bolts is done in the correct order.

7. Once all is assembled, ensure that the cooling system is correctly bled of all air. This can take a while but is imperative that it is done well. Coolant should be

50/50 Concentrate/Water (demineralised water is best)

Hope this helps.

[cackshifter]

I'd add change the oil if you think some has got down past the rings - turbos don't like being lubricated by water! Also be aware if you have to get a new head there are 2 types around, with corresponding gaskets.AFAIK either will do with the correct gasket. And if you think the thermostat caused it, I'd put a new one of them in as well...

[TSD]

I recently had identical symptoms with a TGV lump. Crack test showed a leak from the coolant jacket into #2 inlet port.

If the engine stops with that valve open, when you restart from cold all is well, as the coolant drains away to the sump, or evaporates.

If the valve is closed, it pools on the back of the valve, and drops in all at once on cranking.

My engine wasn't ever frozen or overheated (owned it from new) so you may just have been unlucky like me

[RichardAllen]

Thanks for all the help. My 90 is my only drive, so i don't have the luxury of getting it tested.

From the symptoms and all the advice on here, I can only conclude that my head has a crack in it somewhere. So I have gone for a replacement head and gasket from Turner's. In slower time I'll get the old head tested.

Major points noted around making sure everything is clean and tidy, bolts holes cleaned/reamed, oil changed and proper coolant ratio used, and torquing sequence.

As always the advice on here is comprehensive and authoritative.

Many thanks, I'll let you all know if the new head fixes the problem.

Richard