KV6 looks like coolant leak

[kaiser]

I think the problem is the pressure in the cylinders. Even if you give it power, it will just result in high revs if there is no load on the box.
And the pressure in the cylinders will not be nearly as high, as if you gave it power under load.

The solution is to see if there is exhaust gases in the coolant. There are kits that can do that for you.
If that is confirmed, the next thing is to try and find out if it is a head gasket ( and then which one, if not both) or a crack.


I have seen a couple of blocks with cracks. And if you go to the expense of doing the engine, I would think it might be worth it taking the engine out, and check all liners and surrounds! Cracks here are not unheard of, and the effort of replacing the gaskets and not curing the problem is just too scary!

New, rings, new bearings and the engine should be back to nearly new!
And good for another 20 years!

[xsport]

im sure he will sleep well tonight kaiser. ....

[BillyMG]

Ok well that sounds like a barrell of laughs lol I did try one of those kits with the chemical in which changes colour if there are exhaust gases in the coolant but no sign of anything untoward.

Regards the inlet gaskets they weren't genuine MGR but I did tighten them evenly etc. Wouldn't I lose pressure when pressure testing if that was the issue?

I suppose if we're talking cracks, I could pick up another engine and end up with the same problem again so probably best to address this one.

Dang.

[BillyMG]

How much does the engine weigh??

[SD1too]

Originally Posted by BillyMG

Regards the inlet gaskets they weren't genuine MGR but I did tighten them evenly etc.

Thanks for coming back to me on this Billy.
No torque wrench then?

The inlet manifold gaskets rely for their seal upon a thin bead of elastomer. You can imagine that if this is insufficiently or excessively squashed that the seal could be compromised. I have changed these gaskets a few times and always use MGR branded parts and tighten them to the specified torque. If I was in your shoes that's where I'd start, based upon your report of a petrol smell in the coolant.

But first, try to locate the source of this dripping coolant exactly because that's the route to a successful diagnosis and repair.

Simon

[kaiser]

Originally Posted by xsport

im sure he will sleep well tonight kaiser. ....

Be that as it may.
A friend of mine has changed the head gaskets at least 2 times.
Eventually I pulled the engine, removed all liners, and found a crack under liner no 5.
The block I use to check the fitment of the thermostat housings is also a discarded block. It also has a crack in the aluminium behind one of the liners. So this is not unheard of, as I said.

My own car has started using water, and you can clearly see it in the exhaust.

I have thus had plenty of time to think this one through, and guess what?
I'm going to pull the engine.

And I first tried to replace the inlet manifold gaskets. No luck.

So this is just my take on things! And I could well be wrong, I have been that many times before, but just replacing the head gaskets is a big job in itself. It is not that much more difficult to take the engine out, and give the unit a good going over! And if you intend to keep the car, it makes a lot of sense to do it this way.

[Fred Byrne]

I would follow Simon's advice as starters you have nothing much to lose.
Removing the engine is not as bad as it looks. You just need to have the car under cover and with working space around and oh yes some patience. You leave the gearbox in the car so the weight is not too great. If I were to do this again I would remove front wings and radiator etc and also the oil sump. I found the oil sump kept catching on things as I lifted the engine out.

I removed the engine on my own when I was 82 years old so a young slip of a lad like you should not have an insurmountable problem Just bite the bullet
Good luck!
Fred

[Fred Byrne]

My gut feeling this leak will turn out to be something simple. It is very difficult to see how you can get a smell of petrol from the header tank unless petrol is leaking into the cooling system. The cooling water that Simon refers to returns to the header tank via the small tube that enters the tank at the filler neck. It would be simple to collect a sample of that water and sniff it.
Fred

[BillyMG]

The reason I don't think it's that is it doesn't leak unless under quite a bit of load - like flooring it from the lights onto the motorway. I've got dye in there and there's no sign of it with the engine running on my drive for a prolonged period at operating temp and being given some beans to boot. Plus I put 15psi air pressure in there and it holds - wouldn't one expect it to lose some pressure if it were something simple?

[SD1too]

Hi Billy,

Reviewing your thread I see that this is a tiny leak which you've skilfully captured on video. I'd say that you need to examine that area closely. What part of the engine is it?

It would also be useful to know under what driving conditions your coolant temperature rises to 99˚. When the car is moving you should expect something in the region of 92 - 95˚. 99˚ should only be reached after being stationary in traffic for some time. At 100˚ the fan should bring it down to 96˚. Is that happening?

From my experience it doesn't follow that coolant loss at high engine revs means that the engine has to come out and be stripped down. I had similar with my SD1 and it was a faulty expansion tank cap on one occasion and a failed brazed pipe joint on another. I, of course, received suggestions that a head gasket had gone. On my 75 it was flattened expansion tank cap 'O' rings.

I'm also concerned that you're not addressing the evidence of petrol odour in the expansion tank. That is significant and leads us to the inlet manifold gasket as described earlier.

Regarding your 15 psi pressure test which proved negative, how can we have confidence in that when you've seen with your own eyes drips of coolant oozing out of your engine?

Simon