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80cj 09-23-2001 03:31 PM

how bad is this?
i've been driving my jeep all summer with the top off. sadly i just put it back on this weekend, but when i did, i could finally hear the engine again. i realized that the timing has been set too far forward and that at about 65mph, it was pre-detonating and 'pinging' really bad. so i set the timing back and it has stopped pinging so badly, but it still pings some. also it is blowing oil out the breather worse than ever ( i even ran a hose across the firewall to relocate the breather) so you think the 2 are related. would it have bent the valves or anything? how bad is this?

thanks all

The cup isn't half full or half empty, it's just twice the size it needs to be!!!

elusive 09-23-2001 04:34 PM

Re: how bad is this?
sounds like your rings are about shot, you need a valve job, and all kinds of other "it's time to rebuild" kind of things...

1 ton tj-7 thingy

GeeAea 09-23-2001 05:40 PM

Re: how bad is this?
You could use "extractors" to vent the excessive blowby.

Goto Jegs ( and look at part #720-6002.

commonly used on late 70's ..early 80's GM ..developed by Grumpy Jenkins to relieve crankcase pressure.

Cheap stop gap measure ..especially if you don't have other drivabilty problems (the pinging is probably because of the oil).


Now that I've quit smoking my doctor informs me that I'll die in much better health!!!

80cj 09-23-2001 05:49 PM

Re: how bad is this?
what exactly are extracters? and how do they work? i am intrigued.


The cup isn't half full or half empty, it's just twice the size it needs to be!!!

**DONOTDELETE** 09-23-2001 08:19 PM

Re: how bad is this?
Any time you detonate the motor it tends to eat parts . You probably have a hole in a piston or two that is causing a lot of crankcase pressure . This is the reason for the oil in the air cleaner . You need a new motor . Nothing will fix it , not even the extractors that are mentioned in a reply from Mr. Goodwrench below . Go ahead and buy them . Then you will be out the money on the extractors and the time spent installing them and be pissed that they do not work plus your motor is eating more oil than gas . New motor .

80cj 09-23-2001 09:45 PM

Re: how bad is this?
if that is the case, i can do a compression check and tell. right?


The cup isn't half full or half empty, it's just twice the size it needs to be!!!

GeeAea 09-24-2001 07:39 AM

Re: how bad is this?
hmmm...Mr. Goodwrench...oh well..

The extractors work like a hose syphon. Ya know...the little bottle attached to the garden hose with the chemicals in it....or just like a sand blaster... the flow of the exhaust draws the blow by vapor into the exhaust stream. The backfire valves are just that....they prevent exhaust flow from reaching the upstream plumbing during a "shock event" like a backfire.

These guys are assuming the worst case scenereo for your problem. The detonation can just be oil in the intake stream. This is not an alien event. Oil does that. It doesn't fully combust and therefore leaves a medium to support combustion early in the cycle.

This is not to say that you don't have bad rings. This is almost a given. But that does not mean that you have to put out the enormous amount of cash (even @$150 for a 'yard motor + all the other stuff) if the engine is still otherwise giving good service. Since you didn't mention that you were fouling out plugs every other week or whatever it appears that the top end of your motor is OK (valve guides and seals) and that your cylinder leakage is at the rings. The extractors will eliminate the oil contamination of the intake stream more oil in the air cleaner.

How's your oil consumption and "driveability". Is the beast really lacking in power...does is visibly miss at idle..or at any time for that matter.

Try this: Unhook the aircleaner vent to the valve cover and use it as an old style "draft tube" (you may want to put a longer hose on the vent so it can hang down nearer the ground to save the engine bay the mess). That is, let it hang. If your detonation problem clears up in a few miles....voila`.

The extractors are a simple installation that any decent muffler shop can do. It's not rocket science...then again I think it's darn clever.

It all depends on how deep your pockets are at the moment and/or how anul you are about blow-by in an otherwise fully functional engine.

Good luck!


Now that I've quit smoking my doctor informs me that I'll die in much better health!!!

jeepgod 09-24-2001 08:18 AM

Re: how bad is this?
ya.. what is right above this.. but take that vent line from the rear of the valve cover.. that goes to air cleaner.. put it into a bottle.. milk jug or something.. make sure that is secured in your engine bay.. the oil will then dump in there.. instead of all over the ground.. and blow all over your undercarriage.. this will clear up the rest of the pinging..
do a compression test.. if you have 1 or more cylinders with low psi.. like 120 or so.. then those rings are bad.. to make sure.. squirt some oil down into the sparkplug hole.. and do another compression test.. if it rises up to around normal or higher.. like 150.. then yes.. those rings are bad.. use the air tube into a bottle trick till you can get the rings replaced.. dont worry.. wont harm your engine.. just make sure you check your oil plenty to keep some in it..

<font color=orange>survival is instinct, but living takes guts</font color=orange>

80cj 09-24-2001 08:51 AM

Re: how bad is this?
i did a comp check early in the suumer and they were all around 112 psi. not great but i was told it is most important for them to be consistant. i also already have relocated the breather and run it into a soda bottle. it seemed to work well for a while, but now seems a lot worse...still trying to iron that one out. the engine doesn't run that bad, it doesn't start like it had before, but once it is warm, the performance is tolerable. so i guess my next step is the comp check? correct?

thanks all,

The cup isn't half full or half empty, it's just twice the size it needs to be!!!

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