bad_idea Posted September 23, 2018 Share Posted September 23, 2018 LOTS! I just bought a 90 2.5L 5speed 2WD SWB Comanche. Paid $400 for it and hauled it home on the trailer. PO parked it 2 years ago when the radiator failed, overheated, and he had it towed to the house. Been sitting since. I threw a radiator in it and jumped it. Started right up and ran ok-ish. The rubber 90 on the front of the valve cover is cracked and spewing smoke at idle. I gave it a few minutes to clear up, but it never did. I drove it down the street and back. Parked it in the driveway and smoke was billowing out from under the hood. Popped the hood and there is oil all over the top of the engine. Looks like it was spewing out of the rubber 90 on the front of the valve cover. I assume it's excessive blow-by from worn rings. Are there any other options? I would love for it to be something cheap and easy. I'd like to get some miles out of this motor. I didn't check the CCV line at the back of the valve cover. It may be plugged, but I can't imagine that would account for this much oil/smoke. Could it? I am just scratching the surface on this truck. I will dive into it as time permits. Any pointers? I would LOVE if it could be something simple. Not rebuilding this engine, will yank it and do a motor swap. Hoping to put that off a year or two though. Link to comment Share on other sites More sharing options...
omega_rugal Posted September 23, 2018 Share Posted September 23, 2018 looks like excesive blow by due worn rings, so it overheated? may be a blown gasket too Link to comment Share on other sites More sharing options...
Eagle Posted September 24, 2018 Share Posted September 24, 2018 Never assume. Guesses are good for deciding what to test first, but don't spend money on repairs until you know what you're repairing. If you suspect blow-by, the first test should be a compression test. Remember that all engines have some blow-by, and the Reniix 4.0L engines are known for having the CCV tube get clogged. When that happens, even normal blowby over-pressurizes the crankcase, and that's when you get oil dripping out of the smog tube into the air filter. You may only need to replace the CCV tubing and clean out the valve cover, but the first step is a compression test. Link to comment Share on other sites More sharing options...
bad_idea Posted September 24, 2018 Author Share Posted September 24, 2018 I'll do a compression test on it when i get a chance. I'm with you on not firing the parts cannon. I have the 2.5L, not the 4.0L. It looks like the 2.5L has the same CCV system as the 4.0L, is that correct? I have a 90 XJ with the 4.0L, so I am familiar with the Renix setup. Link to comment Share on other sites More sharing options...
Eagle Posted September 24, 2018 Share Posted September 24, 2018 No, the 4.0L has a CCV tube, the 2.5L has a PVC valve sitting on top of the valve cover. Check to see if the PCV valve is open or clogged. Link to comment Share on other sites More sharing options...
Pete M Posted September 24, 2018 Share Posted September 24, 2018 similar principle though. if the tube that sucks is plugged up, the gasses will escape via another path. Link to comment Share on other sites More sharing options...
Eagle Posted September 25, 2018 Share Posted September 25, 2018 6 hours ago, Pete M said: similar principle though. if the tube that sucks is plugged up, the gasses will escape via another path. Yes, but witha PCV the valve itself gets plugged up. PCV valves are a routine replacement service item, but a lot of owners never touched them. Link to comment Share on other sites More sharing options...
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