Big uh-oh....or maybe slightly smaller uh-oh?

[mrprogrock]

1994 DOHC 3.2L V6....Loud knocking noises from the engine. Sounds like someone's banging a hammer around in there. Also, when I start it I get a good bit of white smoke coming out of the tailpipe. Its smoking a little more than usual when it runs, but nothing hideous. I'm not losing any coolant and I don't see any oil in the coolant. I have not done a compression test on it yet, so I have no info. about that. Valve seals maybe? Timing belt slipped? I'm somewhat new to DIY auto repair, so any ideas and/or advice would really be appreciated.

[2eyefishclaw]

most likely cause is timinb belt tensioner

[mrprogrock]

Originally Posted by mrprogrock

1994 DOHC 3.2L V6....Loud knocking noises from the engine. Sounds like someone's banging a hammer around in there. Also, when I start it I get a good bit of white smoke coming out of the tailpipe. Its smoking a little more than usual when it runs, but nothing hideous. I'm not losing any coolant and I don't see any oil in the coolant. I have not done a compression test on it yet, so I have no info. about that. Valve seals maybe? Timing belt slipped? I'm somewhat new to DIY auto repair, so any ideas and/or advice would really be appreciated.

Yes, I had been reading in this forum about how a bad timing belt tensioner could cause a knock like that. Would that cause the smoking too?

[95.5 Rodeo]

Originally Posted by mrprogrock

Yes, I had been reading in this forum about how a bad timing belt tensioner could cause a knock like that. Would that cause the smoking too?

No, it wouldn't. You should do a compression test on it to rule out a worn piston, rings, bore or all of the above.

How many miles does it have?

Valve guide seals cause engine smoking after the morning startup:

http://www.automotiveforums.com/vbul...d.php?t=196724

Dale

[mrprogrock]

Yeah, I kind of suspect valve stem seals myself. I really only smokes after it sits for a long time, like if it sits over night. When that happens it also can be hard to start.

[knucklebuster2]

Sometimes the smoke is from condensation in the exhaust which accumualtes especially after short trips. The exhaust doesn't get hot enough to burn it off and it gathers in the muffler. It usually is the worst in the morning........

[mrprogrock]

I think I may have found the source of the noise. I pulled the timing covers today and I noticed something unusual when trying to loosen the tension on the Power steering belt. I unscrewed the bolt that holds the swivel mechanism on the pump and discovered that when I pulled on it to relieve tension that the whole pump was turning. I noticed one of the bolts that hold the pump to the engine was missing. When I finally got the timing covers off I found the bolt laying inside the cover. It looks like the bolt may have broken off. I'll have a better look tomorrow, but its looking like this is going to be fun. Also, the plugs on cylinders 5 and 6 were soaked in oil and 1 and 2 had a bit of oil on them as well. About compression tests...what is the proper amount of cranking to get a good reading? I've done repairs on my vehicles before, but never any serious engine work, so I've actually never done a compression test. Doesn't seem like it would very hard.

[knucklebuster2]

I wouldn't worry about the amount of pounds the engine produced during te compression test. Sure there is a formula that uses compression ratio, etc, in order to calculate how many pounds the engine should produce. Of course as the engine wears, this will go down. What I would check is that all the cylinders are basically even in compression. This'll tell you that there are no major problems in any cylinder. There should be no more than 25% difference between any two cylinders.