Thread: 3.9 pressureised cooling system

I guess that nobody has replied since we have been over and over this topic for many years.

Rules of thumb
The only water passages that go from the block are at each end of the block so only 1 7 2 8 can be affected. If the engine shows low compression on 3 5 4 6 ( the middle cylinders) then gasket failure cannot be the cause of radiator pressure. The middle cylinders seem to be by far the most common for slipped sleeves.

The telltale signs of liner slippage are a steam cleaned piston top, and the possibility of a slight drop in the sleeve.

Usually it is pretty clear to see without pressurising the block AFAIK.

Even so the block can be saved by removing the liners, welding the crack which may only be 2-3 MM and fitting stepped sleeves with sealant. This is expensive and time consuming so maybe time for a new or second hand engine.

Regarding the head gasket. They always look pretty crappy around the ends and can leak water out the ends anyway. In my case the blown head gaskets were from the water jacket to the outside with no pressurisation of the cooling sytem. If you have tin gaskets it is usually obvious where they are broken as the tin fire ring is usually breached. On composites they will be like headgaskets on any other car, discolourisation etc and staining of the block and head.
Regards Philip A

Originally Posted by theg

Hello everyone .
I am soon to pull the heads of a 3.9 which is pressurising the cooling system. Will first do a compression test to look for comp variations but I believe I will have to pull the heads after conformation of compression problems .
My question is once I remove the heads what tell tales am I looking for for clues as to weather its a head gasket problem or a sleeve problem . Is the only way to test sleeves to buy a pressure test kit ive seen on the net to pressureise the block to blow coolant past the faulty sleeves and out the top . Ive also read that sleeves drop down slightly into the bore and i guess this is a teltale of the fault .
If there is no sign of a compromised head gasket once the heads are removed will this indicate its a sleeve problem or is it possible a blown head gasket will show no evidence of being blown once i remove the heads ?
Ive seen head gaskets blown before in other makes and its obvious the compromised gasket is at fault but not sure of these 3.9 rovers .
Any help will be greatly appreciated .

I had the same issues with mine. The thing to look for is evidence of steam cleaning on the pistons or spark plugs. (You're losing water?)If you have any evidence of this especially not the end cylinders then you can be pretty certain that you have cracked block/sleeve issues. If you have this on end cylinders then it could be the gasket. I asked about getting the block pressure tested however the local guys said they wanted the motor completely stripped to verify. In my case I'm still not sure if it was the gasket ( I suspect so) but didn't risk it so I went and bought a good runner second hand motor $500, + fit new camshaft/lifters/chain etc. I'm planning on taking my old block to get tophat lined etc etc blah blah blah one day but will see how this motor will go

Also look for a Steamy exhaust and it will run rough when cold + loss of power. Look underneath the oil filler cap to see any evidence of water in oil (mayonaise).

I feel your pain though

first up check the plugs, that'll tell you which pots have failed

typically as the coolant flow is only at the front and back of the heads if its not the first or last pot of the bank then its the liners or the inlet manifold thats leaking.

Thats all the info I needed . Thanks for your help everyone .
Cheers

Hi all .
Got the heads off and no5 cyl is steam cleaned pretty much confirms cracked block . The liner is still in position .
Im not in need of big power so I am considering getting hold of a second hand 3.5 block for reliability and putting the 3.9 heads and injection on it .
Anyone know if this will lead to any fitment problems in the 93 model rangie .Is the camshaft different and if so can it be simply swapped over .
Please put forward your views .
Regards Mark

The camshaft should fit the same for all 3.5/3.9 distributor engines. Your EFI cam, heads, manifold etc should all bolt in/on. A D1 3.5 EFI engine would be the closest fit, made up to 1992 approx. Some early car engines may need some bolt holes retapped for the engine mounts. I am currently replacing a '94 RRC 3.9 with a '92 RRC 3.9 engine for the same reason. There are currently bits of both engines all over the workshop.

Same with mine although I used a 94 Rrc motor to replace the 93.

If I get a good 3.5 bottom end and put all my 3.9 accessories mounts etc on it will everything be in alignment for the belt ? my 3.9 is a serpentine belt model . Also has cruise control mounted on the plenum . Will everything just bolt up and work as normal but just have a less powerful motor ?
I can recall reading something about crank snouts being different lengths on the serpentine motors .