Cooling Problems!

[KittyCamper84]

Right, i'll start from the begining and i hope it all makes sense!

We have a 1984 1.9 DG WBX, we bought it 6000 miles ago and 8000 miles before that it had a recon engine fitted. We've had no cooling issuses, up until about a week ago, when on the way home it got hot and over heated. We stopped and let it cool down and topped up the water. Seemed fine for the next 5 miles or so then did it again. A thorough check over revealed, the metal cap on the header tank had a dodgy seal, so this was changed for a new one and the system properly blead. Took it out the following day and covered about 20 miles with the tempereature running lower than it ever has done, but as we hit the town and slowed down, the temp started to rocket again! Called out the AA, and he did a few checks, finding that our 'new' cap still wasn't sealing properly. He also checked and found no leaks and no combustion gases in the water system. We reblead it and all seemed ok. He followed us home. After about 5 miles he flashed us and said that water and steam were coming out of the back. The temp guage still showed a low temperature. On inspection, he said that the presure was soo high in the system, it had blown past his cap aswell, so there must be something more sinister going on. He towed us home.

Checks for me today were, rad fan switch as this seemed to not work - and it showed up a faulty switch. I also took out the thermostat and checked it as this could cause high pressure if it wasn't opening, but that opens fine in boiling water.

Not sure where to go next? How often do these engine have problems with headgaskets and is that likely?

Thanks in advance for the help!!!!!!

[Ian Hulley]

Sounds like it needs a proper bleed ... as per the wiki, then report back.

Ian

[kervinmervin]

Im no expert at this, but have been through quite a few cooling issues with my van, same spec as yours. Where was the water coming from, I assume it was the top up tank? When mine did this the cap wasn't holding the pressure and instead was pushing out from the header to the top up. It may be worth trying with another one, I think they should also quack when blown, loads of threads about this. The system should push a small amount of water into the header when hot and then pull back when cooling, this shouldn't be much however. It sounds like its not holding any pressure.

Apart from this I can only recommend bleeding, I'm sure somebody more knowledgeable will be along shortly.

[Mickyfin]

You mention a metal head tank cap. Do you know have the darlek type? Mine has, same 1.9DG engine too.

[KittyCamper84]

The new cap was a metal one, is the dalek type a screw on cap? Just completed a compression test and have 9 bar on 3 cylinders and 10 bar on the other, so that and the 'sniff' test by the AA must rule out a headgasket faliure right?

[KittyCamper84]

I couldn't do a proper bleed today, as when checking the thermostat i snapped a bolt and had to fix it!

[kervinmervin]

http://www.brickwerks.co.uk/shop?page=s ... ory_id=118" onclick="window.open(this.href);return false;

This is the one I've got, I think this is fairly standard now.

Sorry to hear about the snapped bolt!

[sjmtlewy]

The old header tanks have metal caps - unfortunately I believe to switch to the dalek cap, you need a new tank, as the old ones have an extra spigot that comes off for the topup (and I wouldnt be surprised if the caps attach differently as well, but I dont know).

New caps available here: http://www.brickwerks.co.uk/shop?page=s ... d=tank+cap" onclick="window.open(this.href);return false;

[sjmtlewy]

A few diagnostic questions for you:

Where does the temp gauge come up to?
Does the radiator get hot?
Do the hot air vents blow hot?

[KittyCamper84]

HI, the temp guage goes to about 2/3rds and then i switched it off and you could hear the coolant boiling. It used to run mid way between the white section and half, and once i had reblead it the otherday it barely got out of the white section. The heater blows hot and the radiator does get hot, but just before it overheats the heater goes cold. It sounds like an airlock to me, but i thought i'd bled it thoroughly - as per wiki? One other thing, when bleeding, what position should the valve in the engine bay be, up or wound down?

[KittyCamper84]

so, just looking at rad caps, is the dalek a screw on cap? If so, it wont fit or resevoir. What is the best thing to have, a new metal twist cap from JK, or a dalek cap with new bottle to match? Surely the metal cap should work ok?

[sjmtlewy]

Im no expert, but reading around posts such as these:

http://archive.club8090.co.uk/viewtopic.php?f=2&t=27985" onclick="window.open(this.href);return false;
http://archive.club8090.co.uk/viewtopic.php?f=2&t=41556" onclick="window.open(this.href);return false;

It would seem that you have either an airlock or a water pump problem.
An intermittend pump problem seems unlikey, unless the belt is slipping, which would probably make a squealing noise.

Things that cause airlocks:
- A leak in the system that's letting air in (holes in hoses, bleed screws not sealing, gaskets gone etc)
- A headgasket failure, letting exhaust gases in. (but you've had that tested already)
- Poor bleeding of the system following work
- The system boiling because it's failing to keep the pressure up. e.g. because the cap isnt working

So..
Check for leaks, which is easy enough.
Bleed it properly (I think the knob should be open for bleeding, closed for running. Its not essential though - mine's completely seized and I've not had issues bleeding). See the wiki for instructions
Get a new cap. Metal ones work fine (mine does), but you must get a decent, high quality one, such as from VW or brickwerks. Cheap ones have been known not to work, and who knows what the AA used.

[KittyCamper84]

right, i've ordered a new rad cap, thermostat and rad fan switch, so when they arrive i'll fit them and give it a good bleed and see what happens!

[KittyCamper84]

Ok, time for an update!

I set to work, changed the thermostat, took out the radiator and flushed it through showing no blockages, changed the rad fan switch, blew through the pipes front to rear also showing no blockages. Refitted all parts (inc new rad cap) and bled as per wiki. She seemed to warm up nicely, so took her for a drive. Covered about 2 miles and the temp guage went sky high and steam everywhere. Limped home and it was boiling in the pipes on the right hand side, but the resevoir was cool??? After careful removal of the cap, large gurge and the level dropped. I topped it up asuming an airlock and went out again. Same thing happened, temp sky high!!!! I noticed that both times the rad fan didn't cut in, but when driving along it shouldn't need the fan?!

Begining to think i need to take off the heads for more exploration, even though the compression was ok and there was no combustion gasses in the water?

Jeremy

[Ian Hulley]

I noticed that both times the rad fan didn't cut in, but when driving along it shouldn't need the fan?!

Did you test the rad fan ? Bridging the thick wire to each of the others in turn ? If the fan or wiring is duff any number of new switches won't fix that. But you're correct it shouldn't need it.

Try the Baxter bleeding method just to rule that out.

Ian