Time to rebuild 360?

[Traveler111]

I am new to these beasts. Please bear with me. It's a 1988 Grand Wag with 130000 miles. Just failed Jersey (tough dyno) inspection. It is getting a some oil in the air cleaner and has one lifter clicking. Oil was rather dirty when I got it. I hate that but the car is pretty clean otherwise.

It idles very fast and when I put it in drive with brake on, it acts like it's running on 2 cylinders. Sounds like a John Deere. On the road it smoothes out.

Should I even bother trying to diagnose the polution problem or just bite the bullet and go for a rebuild?

[Tony Clark]

Time for a rebuild! If you are going to do it yourself, try AutoZone for a rebuilding kit. They seem to be pretty reasonable and get the parts fast. Another good place for Jeep stuff is:"Border Parts" near San Diego. He ships worldwide,and his prices are hard to beat. I've been doing business with him for almost 30 years.
(800)533-0171
Make sure you invest in a good valve job from a honest machinist.A high VOLUME oil pump helps alot too. Good Luck, Tony

[rhamby]

I wouldn't crack the chest open just yet here - that's a decent amount of miles, it's showing its age, and a rebuild is always fun, but I'd check some simple things like the compression. This will give you an idea what the bottom end looks like and an idea where you are in the lifeline. Even a newly rebuilt 360's going to have a little oil residue in the cleaner after some time. I'd say the rough running is more fuel/ignition related. With a rebuild, these things will have to be addressed anyway before you shoudl run the new motor anyway, you know? No fun to break in an engine with a screwed up carb or flaky ignition system. Not saying a rebuild won't be needed, but I'd get everything else checked and fixed before that point - you might have a good motor. Compression test will really give you a good idea.

[Traveler111]

Thanks rhamby, that sounds like good advice. Yuk! I have to pull those plugs again. You almost have to pull the engine anyway to change a couple of those back ones.

[89grand]

High mileage doesn't necessarily mean anything. My Grand has 142k and runs great but I don't have carb problems and my ignition system is about as good as you can put on one of these, MSD and TFI,it helped alot. Plugs are new too. Previous maintenance has alot to do with how long a motor will run but sometimes they just crap out even when you've tried to maintain it properly, you just never know. Also I had a ticking lifter on start up for a while, it would last about 10 seconds then stop, I ran a motor flush before changing the oil about two times and the ticking is gone, so you might consider that too before you tear it apart. It must have had an oiling problem for awhile before I bought it because after owning it several months one of the push rods went right through the rocker arm. I fixed that then did the motor flush twice and it's been fine for almost two years and 25k more miles.

[ June 20, 2003, 09:39 AM: Message edited by: 89grand ]

[rhamby]

Well, I've found that they are so much easier to work on when you neglect to replace all that extra plumbing on there... ;)

Just kidding, officer!

I don't have my readings pre-build, but I remember 7 or 8 was the worst of all.

Have you had the cat checked out? I just recently had to replace mine on my Bonneville w123k cuz it was clogged. Blew out the doughnut ultimately. I have no expereince with them on FSJ's, but it made it run kinda like yours.

[joe]

Do a wet and dry compression test before you open it up. The high idle/rough running thing may just be a blown power valve in the carb and the owner cranked up the idle speed to compensate for the rough idle.

[Traveler111]

Thanks Joe,

How does one check the power valve? Is it part of a rebuild kit?

[joe]

I'm not sure how to test one but someone here prolly does. When you pull the cover from the valve there shouldn't be any fuel or even a fuel smell there. If there is it's leaking. The PV should be part of a rebuild kit. It is in the Borg-Warner kits but I've heard it's not in some.

[mtn goat]

Power valve is in the carb. I second the compression check...wet vs. dry. You may only need a carb rebuild.

[2ndtimearround]

Don't reach for the rib spreader yet :D

Do you have the numbers for HC, CO and NOx from the test? They will help us help you diagnose what could be wrong.

Don't just do a compression test--do a leak down or cylinder differential test. Tells you a whole lot more. See here for more details: http://www.geocities.com/dsmgrrrl/FAQs/leakdown.htm

BTW I assume you changed the oil before the test?

Lawrence

[Traveler111]

Hi Lawrence,

HC = 171, max allowed is 159 - Failed
NOx = 429, max allowed is 1624 - Passed
CO% = 2.86, max is 1.42 - Failed

Yes, I changed the oil before the test. I also changed the plugs. Wanted to change wires etc too (although they look new) but ran out of time before the test.

I will check the leak down info.

Thanks

[steven79]

also check the slack in the timing chain if it is loose it will not help the thing run properly.

[2ndtimearround]

Sorry to take so long getting back.

From what I understand you emissions numbers could mean:

1. High NOx: Check the ignition timing. If it is too far advanced, it will raise the NOx. If the timing is okay, check the operation of the EGR valve. Check EGR valve, EGR vacuum hoses, ported vacuum. You could have a partially plugged exhaust passage that feeds the EGR valve. Could be a problem with your air injection too.

2. High HC: Carb. Check power pump, vacuum lines. Make sure your cat is not plugged.

3. High CO: Carb -- fix NOx and HC first.

Some ideas.....

Lawrence

[ June 25, 2003, 12:18 PM: Message edited by: 2ndtimearround ]