VM diesel advice

[2000 XJ]

Hi Guys

I have the heads off my 2000 XJ diesel due to combustion gasses blowing out the coolant.
Now that the heads are off, what to do?
If i get the heads pressure tested and they are ok, can I just reassemble with a new head gasket and bolts (do I really need to replace the bolts?)
If they find a cracked head or two, will the others be ok, or if it’s been cooked will they all be soft?
Or do I bite the bullet and replace all four heads? Ouch!

I have spent two long already trolling through old threads on this topic!

Cheers in advance

Andrew

[layback40]

Cant work out what the4 pic is. No matter what, the pitting on the right Just below the light colored bit looks bad. If its a head, Looks like over heat. If its looking down a barrel at a piston, looks like rings are a problem.
If you get the corner of a steel rule & lightly drag it across a part of the head surface that is not important, say away from where the barrel seals & not near water jacket holes & it easily scratches the head then it has gone soft. 120 wet & dry should not easily rub metal off.
If the heads were still on I would suggest Chemiweld. I have had plenty of success with it. It may take many weeks to completely seal it.You can get it at supercheap, would have probably fixed the leak.
In putting the heads back on, Hylomar around the head by the liners & around each of the water jacket holes is a smart move. Have been able to reuse head gasket by removing one of the brass rivits & using Hylomar between the metal sheets. I have reused head bolts & broken one before going down the Hylomar route. You can check the length of the bolts to make sure they have not stretched.

[Jumunji-XJTD]

Originally Posted by 2000 XJ

Hi Guys



I have the heads off my 2000 XJ diesel due to combustion gasses blowing out the coolant.

Now that the heads are off, what to do?

If i get the heads pressure tested and they are ok, can I just reassemble with a new head gasket and bolts (do I really need to replace the bolts?)

If they find a cracked head or two, will the others be ok, or if it’s been cooked will they all be soft?

Or do I bite the bullet and replace all four heads? Ouch!



I have spent two long already trolling through old threads on this topic!



Cheers in advance



Andrew

Hey mate
The bolts definitely need to be replaced with new as they stretch.. after you bolt the head back together and torque spec the bolts you need to run the engine up to full operating temperature then cool and re torque the bolts... as for replacement of the heads I would replace all four heads personally but thats up to you .. was it definitely a head issue or just a head gasket?

Sent from my SM-G930F using Tapatalk

[2000 XJ]

Hi guys

That pic is no2 cylinder bore, obvious water marks but not rusted, will clean up ok.

I couldn’t see any obvious damage on the head gasket and no oil water mixed.
I’m suspecting no2 head is cracked. Will find out from pressure test.

Do they crack or just soften and leak somewhere?

I brought this Jeep with this issue so don’t know the history, other that it has not been well maintained!

[Gildo]

Stop now and save your $$.
These motors are the worst thing ever put into an XJ.
If you’re lucky and can get it back together and running sell it to one of the 10 blokes in the country who already have one and are mental enough to buy another.

[layback40]

There are plenty of people around that will knock the diesel XJ. I have found in general that they are petrol heads that have little understanding of these diesel engines.
An iron block/iron head diesel or petrol engine will take a lot of abuse & mistreatment, not so any engine with an alloy head.
Many have an axe to grind having abused one & got bitten.
The VM425 has a lot of other applications including Ford, Alfa, Rover, industrial road sweepers & London Taxis.
Parts a best obtained from one of the many companies in the EU that stock parts for these engines. I have never got parts out of the USA.
Its not a big old style iron petrol engine that can be mistreated.
Looking at that head, it appears that the cooling system has been neglected. The coolant galleries are blocked, probably has been run with dirty water.
A head came into my possession that had a leak under the inlet valve seat. Probably a casting issue. It had caused a similar issue to what you are seeing. If it had been in my jeep, I would have fixed it with Chemiweld. Many knock using it. I have never met face to face any one that has had problems with it when used properly. There are plenty of internet experts that will tell you about all the problems in the world with using it. I once had it in an engine for about 10,000km to completely stop a small bubbling problem.
That head in the pic looks like it may have been re-surfaced. Normally good heads have a slight yellow tint as they have a hard surface treatment. A steel ruler will not scratch them. Have you tried tried to scratch it? If you have, what was the outcome? Have you compared the appearance of all the heads? That will be much more useful than taking pics of the head.
There is every chance that the place you take the heads for testing will have no experience with VM heads.
How bad was the bubbling in the coolant? Did you run the engine before pulling it down?
My previous post comments still apply.
I have reused head gaskets on these engines without issues.
If it is your first time working on an alloy head diesel, best stick to all new stuff. Hylomar is your friend & will stop head gasket leaks if used properly.
Make sure you use anti-seize on the head bolts.
Hopefully you will post answers to these questions so further help can be given.

[2000 XJ]

Hi Layback40

Thanks for your reply. I know these engines get a bad wrap! Yes this Jeep has been neglected and had only water in the cooling system when I got it. I tried chemweld but couldn’t keep water in the system even at idle it would push it all out, so I figured it was to far gone. I got in touch with VM Specialist in the UK and they have good recon’d heads for £95 and also new rocker assemblies and pushrods as they’re all worn. I’m thinking rather than taking the risk with my old heads I’ll just replace them all.
Do you know VM Specialist as a reputable company for refurbished heads? They have new ones for £190?

All the heads look identical and it doesn’t look to me like they have been off before?
I can do the scratch test for you and report back, there does seem to be a ridge around the gasket/bore perimeter on one side of No2 that looks like a crack to me however, where do they crack?

The Jeep is in pretty good nick otherwise, would be a shame to have to wreck it.
I do love a challenge!

Cheers Andrew