1990 1.9 DG Coolant leak/issue

[OldSmithy]

I’m looking for some advice after leaving air cooled ownership and buying my first T25.  Apologies if some of you have responded to my Facebook post about this but I wanted to extend the opportunity for responses and figure out my next steps..

When I went to look at the van I noticed a very small water leak (just a few spots) so rather like air cooled and oil really didn’t think much of this and I now realise I probably should have done much more research.  Anyway, its now too late and I own a 1990 Komet T25 with a 1.9DG engine.  I’d driven it on several short journeys and there. were no overheating issues at all but a continuation of the small number of drops/leak when parked up.   Having read a little about the caps on the header tanks I purchased a new one from Birckwerks and fitted it after making sure I got the quack, quack by blowing into it as I thought this may have been causing pressure issues. I then packed the van to head off on holiday and thought I’d just keep an eye on the coolant.

Admittedly it was a hot day and after setting off we only got about 5 miles before the coolant light started to flash.  I pulled over and could see the leak was much more now.  I therefore limped the van to my in-laws and refilled with water (about 3 litres) so I could carefully limp home after letting everything cool down.  The only change was the cap so may be this caused issues or perhaps it was something else.
 I’ve attempted to trace the leak and it is dripping from a point off the cylinder head between the push rod tubes.   I’ll try to post a photo of this.  In removing the tin slightly I’ve also twisted the head off one of the bolts holding the exhaust on so I’ve got myself another job now, although it was my intention to replace the exhaust anyway as it is so rusty and has been welded several times.

So, all of this rambling is to ask your advice if possible on what I can now do.  Are you able to tell if the leak is likely to be as a result of the cylinder head seal failing or do I need to undertake more diagnostics first to check?

I have checked the thermostat in hot water  which does open and close but I have ordered a new one from Brickwerks anyway as a spare.   The radiator fan works fine when I undertake the wiki paper clip test and I have compression test results of 11bar/165psi across all cylinders

What do I check next? I’m suspicious of the header tank itself or the cap but that is all it is, suspicion at this stage.

Ultimately i know it may be the head seal but I want to have checked everything I can first so any advice is gratefully received, its all a learning process!

Thanks Steve
 

[OldSmithy]

[weimarbus]

Sorry but the heads need to come off anyway to replace the waterjacket seals, you can check then whether there is any signs of a combustion chamber seal failure. fingers crossed that the head studs are ok.

[OldSmithy]

Would I be getting the compression test results I’ve got if the head seal had failed?

I think I’m going to have to chance the remains exhaust bolts to remove the exhaust and then the tinware just to establish if this is where the leak is from or if it is just running down to this as the lowest point and then dripping off.  Is that a sensible approach?

Thanks

Steve

[ajsimmo]

Hi Steve, yes it's (probably) the water jacket seal. I say a tentative probably, as it's possible that it's weeping elsewhere under pressure, and running or being blown towards the underside of the engine. Check everywhere above there for dampness.
And yes, you'd still get good compression readings, even with a leaky fire ring. A leaking compression seal only has to allow a tiny bubble of gas past to pressurise the coolant, but it's a really tiny amount and wouldn't cause a measurable drop in cylinder pressure.

Sent from my ONEPLUS A3003 using Tapatalk

[OldSmithy]

Andrew,

This is the problem I have emailed you about so please ignore that now. I’ll send you a quick PM.

Thanks

Steve

[OldSmithy]

Just out staring at the engine again and can I just check, in the photo below should there be a bolt/nut here like the one at the front of the head? I seem to have three on the other side but for some reason nothing here.

I know I’m probably clutching at straws but anything which may add to my leak is worth checking and surely if this isn’t tightened up then that won’t help will it?!

Thanks Steve.

[maxstu]

Just out staring at the engine again and can I just check, in the photo below should there be a bolt/nut here like the one at the front of the head? I seem to have three on the other side but for some reason nothing here.

I know I’m probably clutching at straws but anything which may add to my leak is worth checking and surely if this isn’t tightened up then that won’t help will it?!

Thanks Steve.

Yes. A head stud nut has broken away and likely reason for coolant leak.   See picture below.

[OldSmithy]

That’s what I was thinking. I guess there really is no option but to take it out and strip it down now. However, I also guess that if I replace the studs the other parts may be ok just to reuse and therefore it could just be a gasket set, studs and time may be?

Thanks Steve.

[maxstu]

Have a read up.


viewtopic.php?p=8205964

[maxstu]

Plus lm doing my very first rebuild on a spare engine.

viewtopic.php?p=8273851#p8273851

[OldSmithy]

Thanks everyone. In today’s update I have some good or bad news I’m not sure which as yet!

I’ve just cut the engine tin on the basis welding it back together will be relatively easy and allow for a better diagnosis as to where the drip is originating from. In good news it may not be the water jacket as it appears to be coming from the small core plug and tracking to the lowest point on the head before dripping off. See picture.

However, in bad news could you tell me if the only way to replace the core plug is still to dismantle the engine/head or could I potentially do this in situ?



Thanks

Steve