Problems to Fix your thoughts?

Ok so I have a 1985 CJ7 with the 4.2 inline 258ci I6 with 216,000 mi I have compiled a list of problems/test/and possible fixes that I would like to run by here on the group. Just maybe someone here will say don't do that or do this. Keep in mind I drive this Jeep everyday and despite the problems it is still a champ on the roads, even if I do take the long way just to avoid highways and any trip that is gonna be to hard on the old girl... Problems: Running rough/vibrating at speed...30-50(can't tell whether its engine or drivetrain) Runs hot at low speeds(

Reply to
jelwell1982
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If the engine compartment is filthy, first thing to do before any work is to take it to a self-serve car wash and take the high-pressure hot water and soap sprayer to it so that you can see where the leaks are, if any. Cleaning the underside of the engine is good too, if you have extra quarters.

As to your cooling system trouble, first check your radiator cap to be sure the rubber gasketing isn't old. This would account for the lack of pressure, and is a cheap fix.

Overheating at any speed could indicate either a low coolant level or a plugged radiator. If the level is low, this also explains the nonop heater.

Diagnose and fix one thing at a time so that you are not overwhelmed.

Reply to
Outatime

Vibration at speed: Maybe your swapped-in drive shafts (why the swap?) but simple things first: When was the last time you had your tires rebalanced?

Oil leak: You've got the 258, infamous for leaking oil from the rear of the valve cover and pretending to be a rear main seal. Mike's got a good rap he does on the fix, the brief version is to carefully degrease the mating surfaces with a solvent like brake kleen (one fingerprint will undo your work), skim-coat the gasket with RTV, carefully place it and torque to spec. Then walk away from it for 24 hours while the RTV cures. No touch, no oil, no start.

Low oil pressure: Perhaps internal wear. Electric oil pressure gauge? Your sender's more than 20 years old, it could be tired.

Running hot: Fan belt shiny? It could be slipping. Your radiator core could be full of sludge. The leaking heater core won't make it run hot, but low coolant can.

Don't go running for a new head gasket until you've ruled out the simpler stuff.

Reply to
Lee Ayrton

To eliminate drivetrain vibes, remove rear driveshaft and put it in 4x4 high with the front hubs locked and drive in front wheel drive for a bit to see if the vibration changed.

I would run a clean rag around the rear of the head after running it for a bit. If wet with oil, change the valve cover gasket.

Mine does that when it is due for an oil change. 10 psi is still OK at idle.

Low coolant will air lock the heater core. Fix leak first and while at it a good flush of the heater core can't hurt.

Not a bad idea, but not really indicated...

Good idea!

Try rag test first.

Are you getting green stains inside the Jeep? Do your windows mist over on the inside when on defrost? Do you have that unmistakable sick sweet smell inside the cab?

If no, then not likely the heater core.

?and I can't build

A bad rad cap is common and will cause that.

More likely a bad distributor cap and rotor and/or wires. How old is the cap and rotor? 258's eat them up often.

To test the wires, open the hood in the dark and with it running spray mist the wires with water. If you get a light show, you need new wires.

A blown headgasket with coolant will make the plugs 'super' clean, just like brand new.

and cause the low oil presure??? and/or the coolant

Nope.

Good luck!

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 'New' frame in the works for '08. Some Canadian Bush Trip and Build Photos:
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Reply to
Mike Romain

Great advice!

I wondered what plugs would look like if water/coolant were leaking into combustion chambers. This would be a dead giveaway, esp. when only one plug were super-clean and the rest were normally gray/sooty. Thanks for the information.

-Outatime

Reply to
Outatime

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