JX Coolant pressure

[superdes]

I'm having some issues with the old JX and am fearing the worst. Hopefully someone with a bit more knowledge and experience might be able to help me out?
My van blew a coolant hose off at the weekend causing it to overheat and stall. The van still starts and runs as well as it ever did and I have been trying to refill and bleed the coolant system using Baxters method but without any joy.
When the van is running there seams to be an excessive amount of pressure in the coolant system. It has blown off the radiator return hose and has also split another whilst just idling on the drive! My initial thought was that I had either cracked the head or blown the gasket when the engine overheated but I'm also wondering if there may be a simpler (cheaper) explanation.
Things worth mentioning...............................
At no point during the bleeding does the rad get remotely hot. I open the bleed screw and cold coolant will come out with no bubbles whatsoever. This is the case after running the engine for upwards of 30 mins. Also, the heater which has always been very good now only blows cold air. No matter how long I run the engine I never get any air out of the radiator (plenty out of the header tank). The temp gauge will climb to the middle and just stay there without the fan ever coming on.
I have removed and tested the thermostat and it opens as it should. I also bought one of those cheap sniff testers off ebay which gave a negative result (I'm not sure if I should read too much into this as I've read you can't sniff test diesels despite what it says on the packaging).
Is head crack/gasket still the most likely issue here or is it possible I just have a blockage or very stubborn airlock?
Any help and advice on what to do next would be greatly appreciated.

[marlinowner]

Think you need to check the water pump.

[superdes]

Cheers for the suggestion, I will have a look at the pump on the weekend. When I rev it, the water in the expansion tank does move but it never seems to drop (as described in the wiki). Is there a good way to check the pumps functioning properly without removing it?

[kevtherev]

The heater to me is the key here.
It does suggest a blockage.
Because the heater is not in the cooling loop.
It just bypasses the thermostat.
By it not getting warm says the coolant is not circulating.


I would attach a garden hose and flush out the pipes to the heater and every other one you can get to.

[mrhutch]

I would be looking towards the waterpump.

If you have the facilities to get the bus in the air, remove the stat and look up into the waterpump housing.

You will be able to see the impeller, and be able to move it with your fingers/screwdriver, or turn the crank pulley (19mm multi-spline - clockwise) and see the impeller turn.

Plastic impellers can come off the shaft or break up

otherwise, bite the bullet and remove the waterpump for a visual check, at about £35 for a new one I'd be replacing it!

[superdes]

A misbehaving water pump would explain a lot, I'll try and get it off over the weekend and have a look. Will also try and flush out the hoses and see if they are all running freely. Thanks for your help.

[superdes]

Unfortunately I think my original fears of head gasket/crack look to be the culprit here.
As recommended I took the stat housing off and could feel the splines in the pump. These seemed in good condition and span round without slipping when I turned the pulley.
I fitted a new hose to replace the one that split and then flushed out the rest of the pipes before attempting to bleed the system again. I started the engine and removed the header tank cap to find smoke bubbling out (wasn't doing this last week). I was sure this couldn't be steam as I'd literally just fired her up.
I had originally done the sniff test using the Blue liquid but have since purchased some of the red stuff as it is supposed to be more suitable for diesels. I tried this and it instantly turned yellow confirming combustion gases present.
I'll hopefully get the head off this week to inspect it but due to the amount of gas getting through I do think it might be a goner. Any suggestions of the best way to proceed here are greatly appreciated.

[kevtherev]

New gasket
Do not skim the head..

[dave friday]

"Do not skim the head"...VW say the same,but lots of people have including me.
But it might be worth putting the money ( for a head skim ) towards a new head!

[superdes]

Ok, so I took the head off the van this morning (surprised how quick and easy it was). The head is an AMC one and doesn't look to have been on the block for too long. The bloke I brought it off said the engine had been rebuilt 2 years ago but he didn't have any proof of this so I took it with a pinch of salt.
There is a crack between the valves on cylinder 1 but all the others look good. Am I right in thinking this isn't an issue?
I couldn't see any obvious points where the gasket had blown but there was quite a bit of oil between 3 and 4. There was also some white spots and a bit of rust on 2.
I should point out that since I have had the van It has smoked badly on startup but clears after 5 minutes of idling or 30 seconds of driving. After it has warmed up there is no smoke under any driving conditions.
Is the best course of action to just clean this up and stick it back together with new gasket and bolts or is there something else I should be doing whilst I have it in this state?

[Oldiebut goodie]

I would hazard a guess that the head wasn't retightened after initial running going by this. I wouldn't just put it back together without checking it is true across all planes. It certainly is a mess around that cylinder! (Glow plugs don't look as though they are ony a couple of years old to me )

[superdes]

I have checked the head with a straight edge and unfortunately it definitely seems to have warped. In the area highlighted by OBG I can fit a 0.008" feeler gauge under the straight edge whereas I can't get a 0.004" under at any other point. Shining a torch behind it, I can also see quite a bit of light between the straight edge and the head at his point but not in others. So what are my options from here?

New cylinder head? Any recommendations as to where I should be looking? Is it worth getting a bare head and changing the valves, cam and bits over from my current one (this seems to be a lot cheaper)?

Good used? I'm a bit wary of this as you never really know what you're getting. They also seem to be few and far between. However if anyone does have a reasonably priced, used JX head I could be tempted down this route.

Skim the current head? I know VW say not to but it seams lots of people do without issues.