Need to know if I jumped timing belt.

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Re: Need to know if I jumped timing belt.

Unread postby dudedog » Wed Sep 04, 2013 3:46 pm

I have a 1988 5 spd. Gas. Lesharo. I am in Utah?Just before the bendex. I broke a timing belt a while back and had one put on and it ran fine to my supprise. I have cought overheating a few times? After the timing belt broke although every once in a while something hits the #1 sparkplug and closes gap? Engine has 145 k on it? This time I was replacing my serpentine belt because of charging issues? My belts especially new tend to get out of alignment easy. Another prob. I got overconfident and drove with the new belt? Serpentine? I heard a very loud bang an my engine slowly stopped. When I saw the belt gone I put on a spare and figured this to be the problem. I found parts of the belt under the timing belt. It would not start and a loud backfire. I towed it. Timing belt was still on. I am not positive but I am pretty sure I did not overheat. No boiling water. I am not locked up and rotor is turning when I crank the engine.The engine sounds strange when
cranking. It backfires and wont start. I felt I jumped the timing belt. I reset the belt and it fills like I lack compression. When I line up the timing marks should the rotor be pointing to the no 1 on the distributor cap. I had a mobile mechanic come by but no tools. The lack of compression is from how easy you can turn over the engine by hand and sound. I hope to get the head pulled soon then maybe I will know more? It still seems out of timebut I went by the book. The mechanic feels the timing was done right. Boththe timing marks on the crankshaft and camshaft show in the book to be about straight up or at around 12 00 or 360 deg? I only need to align up the crankshaft and camshaft right? There is no metal hitting noise when you crank it but it does not start and it backfires. Thanks for any help. It seems like a new engine is the answer. My trans has a slight issue so I cannot justify a full rebuild let alone who to trust. Every time I try to
save a buck on this it seems I get burned. Engines are hard to find. S works says they have one but did not sound confident in it. I have such a lovehate relationship with this. Wonderful when running but parts are getting very hard to get and no one wants to work on this. I am rather tired of driving with my fingers crossed. Am I throwing good money after bad. I wish the rialtas were not so expensive? I need to figure how to do a leakdown test? At least its off the streets now. The city was harassing me on it. Has anyone had this happen? What could the broken serpentine belt do outside of overheating. Frusterated.

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Re: Need to know if I jumped timing belt.

Unread postby dudedog » Wed Sep 04, 2013 4:04 pm

The timing belt was still on. It appeared it jumped and I adjusted it. Still backfires and has a higher pitched sound. The timing marks should be about straight up right. I went by the manuel which can be vague. The mobile mechanic felt it was right. The square hole up and pointing to the time mark on the camshaft. The crankshaft cog and time mark pointing up to the cover bolt like the book shows? It still feels out of time but it seem to be right from the book. The moble mechanic felt it was right. It seems strange I would do so much damage from a serpentine belt? I am fairly confident I cought this before overheating. There was no steam or coolant loss. Does the rotor point to the no one plug on the distributor when the time marks are aligned? I did not check this. I do know the rotor is turning when I crank? Thanks for any help. Thinking on trying to find a good used engine. Not easy. Any comments appreciated?

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RE: Need to know if I jumped timing belt.

Unread postby Scott.Edwards » Wed Sep 04, 2013 4:38 pm

Hi Fred,

If you make sure #1 cylinder is at TDC, and the rotor in the distributor is
pointing at #1 wire, you should be good to go! #1 is at the transmission
end of the engine.

I would hazard a guess that there is something floating in your cylinder
that had smashed the spark plug electrode, so something sure does not sound

Get the timing belt right, adjust valves, compression test, then move on to
other stuff once you are satisfied the mechanical part of the engine is ok.

Regards, Scott

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Re: Need to know if I jumped timing belt.

Unread postby Rick Heslop » Wed Sep 04, 2013 5:11 pm

I just looked at b4-1&2 in the 88 service manual and it appears that the camshaft square needs to be straight up. The crankshaft square also needs to be straight up as well. I had to make the image much larger to see the detail.
Just looked at the 83-86 manual on page E4-1 and the picture is much clearer. The camshaft lines up with the top of the valve cover and the crankshaft lines up with the 'bolt' just above and to about the 12:30 mark.
Hope it helps,
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Re: Need to know if I jumped timing belt.

Unread postby Rick Heslop » Wed Sep 04, 2013 5:36 pm

Just re-read your post and it sounds like all is right with the timing belt. Did you do any checks with the spark wires or under the cap? Could be a mix up of the wires.
Have you tried a compression check of all the cylinders?
All vacuum lines intact?
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Re: Need to know if I jumped timing belt.

Unread postby dudedog » Wed Sep 04, 2013 7:52 pm

I just tried starting the LS and it sounded like it wanted to start ,never did though. I was thinking the loud bang was the valve going through the piston. If the piston is damaged it would be a full rebuild. If this were thecase would I not have a loud deep thumping noise. When it tried to start it was a very low rpm but did not sound horrible. There is nothing clanking just previous backfire. I still feel there is valve damage. I have not compression checked it yet. My compression tester has to be held in and the mechanic did not bring his. Greg sugested a leak down test which I need to figure out. I am assuming no compression from the sounds and ease of turning over the engine. I will do this when I can. Do to the age and mileage I would like to find something more reliable. Engines are hard to come by. Mobility does not have one and s works has 5 and he says he would not aprove any as usable. I have always had problems with the wrong mechanics on
these so I am leary to have it rebuilt. Wishing I only have to do the upper end then it would be worth it. The spark plug issue has happened threetimes w many miles between but something is comming apart. Thanks for the replies and tomorrow I will check tdc with the rotor but I dont see the timing being an issue at this point.

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Re: Need to know if I jumped timing belt.

Unread postby RonOhler » Wed Sep 04, 2013 10:57 pm

If it is suspected that the valve got bent it should be easy to check sincethese are solid lifter engines. Bent valves will not seat fully which thenleaves the lash very loose.
This should not occur in the gas engine as they are a non-interference engine.
I suspect the valve timing is wrong or the ignition timing is off.
I've had sparkplugs close the gap twice for no apparent reason. Both times it was the same cylinder. I've put nearly 4K miles on the rig since it first happened. Larry believes it is caused by pre-ignition and I am going to concur with that belief. The plugs in my rig were definitely running hot(nearly white in color) so I dropped a heat range. I've not had an issue since. The manual for my 92 LS calls for premium grade gasoline when operated in hot temperatures or under heavy loads. This indicates that the engine really does need a bit more octane than pump regular provided - 20 years ago. I don't know to what extent standard octane ratings of pump motor fuel has changed - if any - since then.

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Re: Need to know if I jumped timing belt.

Unread postby Roberta Radavich » Thu Sep 05, 2013 2:13 am

This is only a memory, but once when we had a loud back fire and
a no start condition afterward, it turned out the backfire had popped
loose the ... I think it was the air intake up front, in the general
area of the driver's side headlight, this fat rubber jobber about 4
inches in diameter that was supposed to be attached to it's pipe by a
clamp, and it had simply been blown off by the backfire. It wasn't
that noticeable, and we would have missed this altogether but for the
good advice of a mechanic. As soon as we reattached it, all would
again start and run. It sounds like you may have more wrong than that,
but I just throw this out in case there is this simple thing wrong
that is confusing your other issues.

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Re: Need to know if I jumped timing belt.

Unread postby lsrschoppe » Thu Sep 05, 2013 6:18 am

Fred, I will go with what Roberta suggested. On the left (drivers side)
of the engine compartment is the air cleaner. Follow the flow towards the
engine and find the big hose elbow attached to a big unit (air flow meter)
on left forward end of the compartment. From there a hose (part is
convoluted) turns down and goes to the J-tube attached to the throttle body.
If the convoluted hose becomes detached from the air flow meter or leaks
air through the bendable part due to rotting, rough handling or otherwise
damaged, the measured air amount passing through it becomes changed, adding
air that gets through the damaged section that is not measured. This in
turn is not what the computer saw and cannot be compensated for. This added
air causes trouble other ways, can change the mix, and cause backfire, no
starts and other problems.
I suggest that you remove the convoluted hose and carefully visually check
it, especially in the folds where it tends to tear....tape is not a fix if
you find tears, I have done emergency patching with black vinyl glue but
that is not a permanent fix, the only recourse is replacing it......if you
can find one. there are some fixes using hoses that will sort of substitute
but hurts performance.
The convoluted hoses are rare finds, and as such are expensive. Perhaps
someone will have a spare in good condition that you can buy if yours is
Good luck with your problem.
Remember that the cylinder closest to the firewall is the nr. 1 cylinder.

The book gives exact steps for locating and positioning the crank to TDC
which is the first step in checking timing. See and follow the step on
pages B4-1 to B4-4 in the 87-89 service manual.
You might be "overfixing" by not starting with basics. You will find this
very costly if you are having the work done at a garage.
Again, hope you find a fix and get back on the road.
Larry S.

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