Loud ticking (knocking) from under valve covers


kingdeer
02-15-2005, 08:59 AM
Kid has a '91 LeSabre with 3800 engine and 165K miles. He asked me where I keep the oil, because he thought he needed some. I went out and checked dipstick (I changed oil less than 1000 miles ago), and it read full. He said it sounded like it needed oil on his way home last night, and started it up. Loud loud clicking - so I pulled oil cap off - no sign of oil kicking around - so I'm thinking oil pump here. No other apparent problems with this car. Does it sound like oil pump to you? And if so, is it in the pan or somewhere else - I imagine if it's in the pan, it could be a pain to get to. Any ideas and suggestions would be greatly appreciated. Thanks in advance, Rick

gbeeley
02-15-2005, 12:43 PM
Location of oil pump: it is mounted on the inside face of the timing chain cover, which is right behind the water pump. The pump is basically two gears soaked in oil between the timing cover and a plate. An elegantly simple device. If it needs to be replaced, you likely will end up having to replace the entire timing cover.

So is there any noise from the bottom end, or is it all just up at the top? And is it from just one valve cover or both?

The noise - could be a bad valve lifter if it is just from one valve cover. If you hear lots of ticking from both covers, suspect low oil pressure. This motor has hydraulic lifters and if one goes bad then you get a ticking noise from up top. I think low oil pressure can cause lifter noise, but really the way to find out is to have an oil pressure check done. (if you have the gauge in the dashboard, that can provide some indication too). If the pressure is OK, suspect a bad lifter, if it is not OK, suspect a bad oil pump or worn bearings.

Other potential sources of the noise - 1) broken or damaged valve spring, 2) piston slap, 3) rod knock or wrist pin knock.

If your oil pressure has suddenly gotten very low, check for coolant or other contaminants in your oil. I recently read a very good article on problems from this at:

http://www.blackstone-labs.com/newsletter.html

But I'd be hesitant to run that motor if the noise is bad.

kingdeer
02-15-2005, 12:55 PM
I should have posted earlier that noise seems to be coming from inside valve covers - particularly the one next to firewall. Also, the oil pressure guage on dash is reading normal - not low or anything.

gbeeley
02-15-2005, 01:35 PM
If it is coming from both valve covers, especially if it started over a very short period of time, I'd suspect something systemic. I have heard that the gauge on the dash isn't a super-reliable way to check the oil pressure, but not sure to what degree....

I'm not entirely sure if it could cause the noise (crank pressure would have to get awfully high), but you might check your PCV valve - to check place a piece of saran wrap over the oil filler opening (cap off) with the engine at idle; there should be a slight amount of vacuum drawing the plastic wrap in (don't let it actually go in there!). PCV valve on this engine is a PAIN to replace - because it is wedged so tightly in there....

Other than that the only thing that I can think of is low oil pressure at the lifters. Maybe someone else here can shed some light on it...

tman
02-15-2005, 03:28 PM
Before throwing down lots of cash on an oil pump, I'd pull the valve covers, and use wd-40 and brake cleaner to free up the circular things on each side of the lifters. This may help the ticking, although it could still be a pump. Make sure to thouroughly flush the oil after doing this. Might be good to stuff a lint free rag down the openings in the head, so you won't have to flush the entire engine.

Add your comment to this topic!