Question about 1988 Jeep Wrangler

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We have a 1988 jeep wrangler with a 4.2 litre 6 cylinder.

At Idle everything seems fine, timing is 8-12 btdc and idle is around 750 -800. When I take it for a ride at highway speed It looses power around 3,000 to 4,000 rpm and looses oil pressure. When I return to the garage there is tons of oil inside the air cleaner and when I check oil level it is lower but seems to be like air bubbly. Please help, not sure what to think

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  • rbhall332 Feb 07, 2010

    Hello there, thanks for the answer. I have a follow up question. The engine came with the pcv filter in the front hole and continued to the bottom of the carb for vacuum with drawl. The back hole had a plastic piece which was for fresh air intake from the air cleaner. I have taken out the PCV filter and cleaned it thoroughly in my parts washer.It seems to be functioning properly. I even switched the PCV filter to the rear and put the intake piece in the front. The problem still happened, Could the PCV filter still be bad or do you think there could could still be problems inside the valve cover. Also I noticed that when I pulled the dipstick to check the oil level Smoke came out of the dipstick tube. Thanks Again

  • rbhall332 Feb 07, 2010

    Still had a few questions but it was helpful


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Hello, I believe I can help you with this problem. The oil in the air cleaner is "blow-by" from the piston rings. This is a common problem on your engine. There are 2 breathers built into your valve cover, the rearward one is the PCV valve and is most likely clogged up causing the front causing the crankcase pressure to go through the front breather and on into your air filter. Chrysler sells the parts you need as a kit, with the grommets for the valve cover and the vacuum hoses to refresh your system. You will need to remove the valve cover and clean the inside of it, then replace the grommets and hoses to the air cleaner. If this doesn't work you might need to replace the entire valve cover assembly. This is most likely causing your performance issues also. Good luck and don't hesitate to ask for more information, I'll be glad to help.

Posted on Feb 06, 2010

  • BeninVa
    BeninVa Feb 06, 2010

    Ok, I don't believe I wrote that but the following sentence should have read:
    There are 2 breathers built into your valve cover, the rearward one is the PCV valve and is most likely clogged up causing the crankcase pressure to go through the front breather and on into your air filter.

  • BeninVa
    BeninVa Feb 07, 2010

    Hello again. I'm glad I could help you with this. Yes, the smoke coming out of the dipstick is definitely a sign of too much crankcase pressure. If you are sure the hoses aren't clogged and there is good vacuum, I would recommend a thorough cleaning of the inside of the valve cover, including the snorkels inside. If there is heavy sludge buildup you may need to clean the head as well to open the oil return passages.


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