Help - JX engine coolant mystery

[julieewendubbus]

Hi, hope you are all well; can anyone offer suggestions to help me with my coolant crisis? 
My 1988 T25 has the original 1.6TD engine (JX engine code)
I'm loosing coolant when driving. Over the course of about 100 miles, the header tank level drops, then the warning light comes on, and the temperature gauge rises. 
The expansion tank (behind the number plate) gets overly full, suggesting a circulation issue?
The garage I use have been super helpful and investigated extensively, but the problem is still there. 
I have had the following replaced:
water pump
auxiliary water pump
header tank cap
thermostat

The garage have ruled out head gasket, the system holds pressure, and the problem does not manifest itself when in the garage. They have left it running at high revs for several hours and checked for a leak, they have done a "sniff test", they have used a machine that sucks all the coolant out and holds a vacuum for several minutes before refilling the system. It won't refill the system if it can suck air out of it. 

The van has done 188,000 miles. It is a bit of a dirty diesel and does burn oil when driving under load, but it is smooth and will sit at 60mph happily. 

Any suggestions for things to try gratefully received !
 

[TONYT25T25]

Not the same model as mine, but could be the header tank cap even if you have changed it, ie not allowing the return of coolant from the top up tank. Could be worth doing a research on the header cap test (dalek) one is called the quack test but heard that is not a guranteed test,.

[R0B]

There are some dodgy caps out there. If you haven't already I suggest you buy one from here.
https://www.brickwerks.co.uk/header-tan ... 3-oem.html
Although it does puzzle me the garage can run it for several hours with no problem. But this happens when you run it.

[Rascal]

surely when they do a pressure test they have to remove the cap and replace with one attached to a gauge etc, hence removing the potential faulty cap from the system therefore they cant see the issue ?

[clift_d]

It doesn't sound like you're losing any coolant, only that it is migrating from the expansion tank (this is the main tank with the blue 'dalek' cap) to the reservoir (behind the number plate) during use. In my experience, this is a classic indicator of head gasket issues with a JX, so I'm not sure what to suggest other than maybe taking it to another garage to get a second opinion / 'sniff' test.

[davidoft1]

Try a new genuine cap first , also check the cooling fan usually kicking in

[Oren Kipnis]

Either a head gasket problem, or may be even cracks in the cylinder head itself.

JX engines have gained a reputation of cylinder head problems in different markets, especially if they suffered a short overheating.

While pressure testing the cooling system, I believe that the engine was cool, thus narrowing any crack which would widen once the engine heats up.

I would have another workshop have a look of your van.

Oren

[julieewendubbus]

Thank you everyone
It is the brickworks header cap I have purchased (twice, in case I got a duff one)
It seems my next course of action is engine investigation- either with my current garage or I need to find someone else local I trust
Given that the oil consumption (the burning oil under load) has increased I guess there is something sinister going on.
Perhaps a refurbished JX lump is my best bet?
Or maybe the replacement cylinder head that just kampers have for sale??

[clift_d]

If you are considering a replacement JX then the best people to speak to would be AW Engineering in Darwen. As far as I am aware they are the only people currently providing properly remanufactured diesel engines. It won't be the cheapest, but it'll be the closest thing to a new engine.

[Oren Kipnis]

In case of going for a rebuild/replacement, I would suggest skip the JX and find an AAZ,
It is 1.9 equivalent with a mechanical pump, and will fit using the JX peripherals with need for any modification.
It will be stronger, and mush more reliable.

[julieewendubbus]

Thanks - lots of great info here.
Have considered engine options and I wonder if just swapping the cylinder head is an option ?
The part is available and is 1/4 the price of the refurbished jx lump. But if the problem is elsewhere in the engine I’ll still have a problem.
https://www.justkampers.com/068103265e- ... -1992.html

Budget is not massive, and I’m not convinced I want to deal with the hassle of insuring the van with a non standard engine, so I think I’ll not go down the aaz route. It’s already tricky to insure as it is a left hand drive import.

Thanks y’all

[Rascal]

Have you tried claassic line.. No problems insuring my LHD import? Club discount aswell

[ajsimmo]

Insurance isn't usually a problem with an AAZ upgrade, makes little or no difference to the premium in my experience. The bigger problem is finding one. They've more or less fallen off the end of the conveyor belt of time... I got a great one earlier this year from a member on here who removed it from his van to go Subaru, but I'd been looking for months. There's no mk3 Golf donors left, and just a few manky T4s.
I think the best option is to get your head gasket done on the JX, and the head pressure/crack tested whilst off. Don't let them skim it. If it's warped you'll need a new one.

Sent from my moto g(30) using Tapatalk

[julieewendubbus]

Thanks; I think I will stick with the JX engine. The next step I am planning is to get a reconditioned JX engine from AW Engineering and have my garage fit it.
I've spoken to the garage, and they have done a sniff test more than once, so are certain it is not the head gasket. More likely to be something in the cylinder head. As the van has started using way more oil than it used to it seems best to change the whole lump, rather than just the head. 
AAZ engine is tempting, but the price is too much for my budget 
Looking at £2k for a reconditioned JX, and £3k for a the AAZ. Plus fitting will be a bit more involved with the AAZ, so garage c costs likely to be more as well.
Thanks again everyone