Diesel XJ's - How many of us have 'cooked' it?

[kyro]

keep us posted on what you do

[Deezelweazel]

So it is time for some Diesel facts:
As a german Diesel XJ driver I can tell that 90% of all german Diesel drivers had already a head failure.

It is causes by cracks between the inlet and outlet valves or by cracks between the water channels and the precombustion chamber.
Overheating and insufficient water supply due to the split head design is the cause for that.
Im at 107kkm at the moment and have taken several precautions against head
failure:

- Intercooler air flow improvement.
Slots in front of the intercooler increase air flow. It is important to seal the Fan shroud behind the intercooler against cross air flow to increase visco fan efficiency.

- visco fan
Cleaning and taking off the corrosion of the visco fan front increases efficiency of the fan.

- adding an oil cooler
Knowing the fact that the 2.5 has an water/oil cooler leads to support heat exchange.
Remember the heat law: Heat flows from the hot side to the cool side - not vice versa!
So you can use oil to transfer heat!!

- restriction free radiator
the manual doesn't allow an obstructed radiator (bull bars, aux lights)

- proper warmup/cooldown procedures.
The head consists of drop forged aluminum. Its very sensitive against overheat.

It is neccessary to warm up the egine carefully and to check oil temperature before hitting the pedal. Cool down is also important. Go easy before you reach your destination and idle the engine up to two minutes. That takes alot of heat out of the engine.
Recheck the temperature after a hard drive.
The engine can heat up itself up to 110°C-up to half an hour after the ride!!!
Thats one of the causes for head damage.
most germans implant a water cooling aid: ´a simple aux water pump to assist cooling and water circulation after engine shut down.

-Head failure recognization
Remove the water bridge on the heads- bubbling air indicates the cracked head.

- To ensure reliability of the engine:
the coolant system must be in top shape

- replace the waterpump

- check coolant level very often

- check the radiator- the end tanks are made of plastic and like to leak after 10 years, the radiator likes to corrode, its made of copper instead of aluminum, make sure your replacement is also copper- it has a better heat transfer capability.

- always use the proper coolant mixture
be alerted when the heater hoses aren't both hot to the touch, it's an indicator for weak water pump!

-Flush the coolant system often!

-Do not close EGR!
It takes heat spikes out of the engine during part throttle. It's closed under full load anyway!
Only advantage is reduced soot in the intake.

We found out 100.000km is the critical distance. Heads can fail anytime after this distance without taking care of it.

I hope this is useful information.
I'm working on the Diesel engine since 2 years now and there is a lot of knowledge to share.
Michael, the Deezelweazel

PS: It is possible to do a lot more. But that depends on your personal view and wallet. e.g.
extruding hone of the heads, cooling control systems...
Feel free to contact me.

[MudMonkey30]

Thanks for that Deezelweazel!
Always good to see and hear from other Oil burners as myself!
I was also thinking of adding an oil cooler setup but still not 100% sure where to install such an application that won't get damaged offroad!
Have you got some good suggestions?

[MudMonkey30]

Oh and to keep the original thread going, I bought kryo's off him and the only real issue I've had was the thermostat breaking and only letting 1/4 of the properwarer flow through, so nothing yet( knock on wood)

[Deezelweazel]

Pretty simple to answer:
Mount it behind the bumper next to the intercooler. Provide airflow with slots or a fan.

The oil cooler was installed in other engines using the VM engine to.
e.g.
- Alfa Romeo 155
- Ford Scorpio
- Opel or Vauxhall Fontera A

The cooler must have a surface of at least 500cm² to work efficient.

An oil cooler alone is not enough!

[BwanaBob]

I'm not from Australia, we're over in West Africa, but here we've had the same experience with the diesel Jeep. We bought our 98 Cherokee Sport in 2002 at 72,000km. It had the VM 2.5TD. In the next 50,000km We had a couple of water pump failures, some overheatings, and a motor rebuild top and bottom with some used heads that had been tested. The new sleeves maybe weren't pressed down enough and we had a hard time getting the heads to seal. When the bottom mains gave out, I decided that this motor was too expensive for my means and too complicated for the mechanics we have here. Seeing it sit for a couple months with no engine and rusting away made me ready to do something radical.

It now has a Toyota "L" naturally aspirated 2.2L diesel, from an old Toy pickup. That is a big comedown in power- only has about 60hp. It takes a long while to get up to 90km/hr, if it ever gets there. But it does fine on the trails where I really need it. The engine is lighter than the original so the suspension doesn't bottom out nearly as much as before. Consumes 12 liters per 100km. Has the original 3.73 Dana 35 rear end. Not much power for 4wheeling. There are other Toy motors with the same block with more displacement and turbos and electronic fuel injection and with all that you can get up to 90hp. But I wanted this to be real simple, mechanical, nothing electronic. Everybody here can work on this engine and parts are abundant and reasonable.

The mechanic swapped a Toyota input shaft into the transmission and the Toy bellhousing bolted right up. He adapted the clutch's hydraulic hose from the Jeep's master clutch cylinder to work with the Toy's slave cylinder (external). The motor mounts were made up by a local welder but hang on rubber bushings like the originals.

Here is the thread that gave me the idea.
http://www.jeeps-offroad.com/f41/eng...housings-4740/