Engine Mechanical problem
1996 Chrysler LHS 6 cyl 130000 miles
Replacing timing belt, found that both cam sprockets are 180 degrees out of position. Is there a reason someone would have done this, or is it just a mistake? I want to set the cams back to correct TDC position, but if they were set 180 deg out to solve a problem I should keep them as is. Thanks in advance for any help.
You sure engine was top dead center #1 cylinder? #1 needs to be up on compression stroke if you had it at top of exhaust stroke cam align makes would be pointing down 180 out. Pull #1 plug rotate engine put your finger in plug hole when you feel hear air rush out that is top dead com. Stroke. Everything should be aligned.
September, 23, 2008 AT 5:47 PM
Thanks for your reply Doc. I haven't checked the piston positions via plug sockets, will do tomorrow to confirm. But here are a few more details that will explain why I think the cams are 180 deg out: I removed the timing belt cover and used a socket to turn the crankshaft sprocket until the alignment notch on the sprocket was in line with the TDC mark.
The timing belt was still on. The camshaft sprockets each have a punched alignment dot which at TDC should line up between two punched alignment dots that are above the camshaft sprockets, on the timing belt casing.
But when the crankshaft sprocket is at TDC, the camshaft sprocket alignment marks are not immediately below the casing dots, at the top of the sprocket. They're on the bottom of the sprocket.
My Haynes repair manual description and pictures show that the sprocket marks and casing marks should be beside each other when aligned, not separated by the diameter of the camshaft sprocket as they are on my engine.
Since all this is clear as mud, I'll try to post a picture asap. Thanks again for any and all replies to my question.
September, 24, 2008 AT 11:34 AM
The crankshaft turns twice for one rotation of cam so you can have crank mark lined up but not on compression stroke of #1 your on the exhaust stroke.
4 stroke engine intake, compression, power and exhaust. WARNING you have an interefance engine any rotation of crank or cam without belt on will result in valve damage. DO NOT TURN ENGINE put belt back on rotate crank 180 cam marks will move to top and you then can safely change belt. Trust me your engine is NOT 180 out IT WOULD NOT HAVE EVER RUN
September, 24, 2008 AT 12:21 PM
That's the explanation I needed, I knew I was missing something simple. Thanks Doc.
September, 24, 2008 AT 1:14 PM
You are very welcome I would have felt badly if you would have damaged the valves costing $$$ which none of us have much of these days.