Tell me it ain't so...

[Dominic]

Would someone please reassure me that I don't have a blown head gasket or a cracked head.

'91 TZD, performing superbly, starts on the button, nothing untoward coming out of the exhaust, or goop or soot in the coolant (or oil), but once up to temperature, it looses up to a litre of coolant out of the bottom of the rad. This is particularly noticeable if the car is driven say 5 miles, then switched off, when it drips incessantly.
The system doesn't seem to be over-pressured, but when the header tank cap is taken off with the engine hot and running, what's left of the coolant is definitely fizzy, however the fizz doesn't smell and it's not dirtying the water (which it would if the fizz was caused by combusted/combustible gas). On cold startup, there is no coolant disturbance to speak of.
Could it be a fissure in the rad which only opens up when it gets hot, or something more sinister?

And another thing, on my daily 40 mile back lane commute, it seems happy enough, but on a motorway, it overheats, even if the coolant is full after no more than few miles.

If it is a head gasket, are there any words of wisdom in the invaluable archive here?

I'd be grateful for anyone's thoughts on this.

[Mothman]

Hi bud,

fizzing or bubbles in the header tank usually indicates a blown head gasket[this was zakly how my TZD behaved when i got her in April]
However, i think you actually need to find where the leak is coming from, either the rad or a ruptured pipe and go from there.
There are many many threads about head gaskets on the forum, may be a good idea to search the forum for an idea.

Good luck.

Andy

[citronut]

firstly do do the rad fan/s kick in as they should, secondly i would try a bottle of Kseal in the coolant and make sure the system is bled of any air thoroughly,

regards malcolm

[citsncycles]

The fact it has to get up to temperature before leaking may be a red herring - it may have a slight pressurisation issue that doesn't show until the thermostat opens and allows the pressure buildup to reach a weak spot in the rad.

May be the beginnings of head issues, but may be back pressure due to a blocked cooling system.

[mat_fenwick]

firstly do do the rad fan/s kick in as they should, secondly i would try a bottle of Kseal in the coolant and make sure the system is bled of any air thoroughly,

The fans only have an effect when moving at low speeds, so overheating on the motorway won't be anything to do with that. Still a good idea to check though...

I've had positive results with K-Seal on another vehicle with a suspected cracked head, and have recommended it on here previously. However, I wouldn't recommend it now on a BX as it can leave deposits in the heater tap. Vanny has stripped a few down to find partial blockages which can and do cause breakage of the ceramic slider.
You obviously need to make sure it's bled properly, but if no work has been carried out on the cooling system recently it shouldn't develop an airlock!

Is there any pressurisation from cold after a minute or so? I.e. before heat has built up pressure there should be nothing else to cause a hiss when undoing the filler cap.

[themildbunch]

My TD started and ran fine and before I knew any better I missed the signs of head problems when I bought it some years ago now..

There was no oily water / milky oil, excessive white smoke from the exhaust or overheating.

There were bubbles in the expansion tank and more movement when the engine was revved... There was also a distinct psst of pressure when you took the cap off the expansion tank after only 20 - 30 secs of starting the engine from cold...

I got it done as I liked the car but I've read posts of people carrying on like this for 1000's of miles before it gets really bad or chucking some 'stuff' in the cooling system to get it to last a bit longer but you'd almost certainly be clogging up the heater valve doing this...

[Wooscary]

Mine is definitely getting a bit bubbly and there is clearly a bit of pressure building up (although not as quickly as a few seconds).

One of those things that will need doing I guess. Maybe I should go for a third replacement engine is called for?

[Tim Leech]

Ive heard of a 19tgd last 5 years with bubbles in the coolant before the headgasket gave up totally!

[citsncycles]

All depends on where and why it's failing and how it's driven I s'pose - Mine would last about 5 minutes

[barry badger]

I would fit a new radiator and then see what happens, the overheating could be due to a partially blocked radiator core which only produces symptoms at higher speeds/load. As a general rule i've found with xud engines if the cooling system is properly bled the radiator cap should come off with a slight hiss on a fully warmed up engine, if the cap won't come off without any water spraying out the head gasket is gone.

[Mike E (uk)]

I would not pour any goo into an engine of mine, the heater valve is not the only thing that can get blocked.

Best fix the problem properly if you want to keep the car for more than a few months.

Mike

[kiwi]

I took me 18 months to finally figure out it was the headgasket on the first of the 19TZS I had. Big clue came when it would not start after a couple of weeks parked up and one of the cylinders was full of water. I think the 160kph blast the day before it was parked up may well have blown what was left of a gasket as well

The same vehicle is showing signs of another Head Gasket failure however is not in regular use so my park it up theory don work! But there is a blockage in the cooling system to the Heater Matrix! My guess is that this is where my problem is it is worth excluding all these ideas first before assuming HG failure!!! Also check the hose clips sometimes a leak can show up under pressure (eg Motorway driving) and majically fix themselves at lower revs/speeds and temperatures.

[Mothman]

I think its your head gasket, take the head off and have a look.

andy

[andycadabra]

I would not pour any goo into an engine of mine, the heater valve is not the only thing that can get blocked.
Mike

having got through 2 head gaskets in 2 1/2 years, I've used them all - K Seal [x 3], Steel Seal, bar's leaks. They didn't work and may have added to the problems of the scaled up radiator I'd used for far too long. But when the heater tap had to come out [broken due to the stupid garage taking the engine out from underneath] it was in perfect working order, no sign of any stiffness. I think most of the problems like that are largely because sand was used in the past?