Hey guys, I've been looking for a project and the XJ's look like my kinda thing, they look tough, all the ones I want are 4x4 and they seem to have an endless aftermarket support.

I found one I can get for dirt cheap off of a AF guy, I've been told it needs a head gasket, and a head. Also it has good compression on 1 and 6 but the rest have poor compression, my thinking, and the owners, is that it was over heated and the head warped causing the lost coolant and the poor compression.

The guy has a head for it so its pretty much just my labor that I'd have in it.

Lemme know what you guys think! Thanks!

 

all i can offer is my 89 has been very dependable thru the 15 years ive owned it never left me stranded the only thng about 87 thru 90 xj the are known as renix models renault did the electronic in them the systems are a l;ittle more trouble to problem solve as there is no code reading set up or a check engine light they have a little less hp than the newer ones ,the 89 year is the third most produced ,the factory dana 35 rear is a nonclip rear which is a little better than the clip rear models, the cooling system with the pressure bottle is a very troube some system upgrading to the newer rad system is a must when you can afford a new rad and over flo bottle

 

as for the warped head it takes a lot of heat to warp a cast iron head

 

What if i just replaced the whole motor, that would fix it all....

 

A 4.0 swap is one of the easiest motor swaps IMO. THey are extremely reliable and pretty common and cheap. They are know to last 350k miles. You can get an amazing quality rebult long block from Titan Engines if you don't wanna rebuild yours or swap in a used one.

 

Compression is typically affected by the valvetrain (valves and associated components). If you get a new complete head chances are the compression will be better. Or, check the valves (seats, cam, springs, etc) and/or get a valve job done.

Compression checks are good, but if you do a power balance test on the cylinders it might provide more info. This test measures the rpm while you disconnect/re-connect eacy cylinder. If the rpm changes the same amount for each disconnected cylinder, the power is balanced and each cylinder is 'equal' in power.

Another good test is a leak test. Compressed air put into each cylinder and you listen for leaks. For example, if the air blows past the rings and into the oil pan and out the oil dipstick tube, you have other issues.

If you know for sure that it needs a head gasket, then taking the head off and checking the lash and valvetrain stuff is the perfect time. You can also put a straight edge on the head and measure for warpage with feeler gauges (you need to check the valve lash with them anyway right?) Don't forget to check the deck of the block too.

If it's a good deal, I'd jump on it as long as the tranny, running gear and drivetrain are good.

I'd go with a 4.0 ENGINE. Hard to feed a 'motor' gasoline. An 4.0 is an internal combustion engine. Sorry, I get a little technical on forums.