Engine Noise

[Tiggie]

The 88 has an interesting engine noise. Happens when it’s warm and sounds like a hollow pulsating whirling sound. Couldn’t get a decent audio clip yet. It’s isolated to the rear drivers side in the middle of the engine block as best as I can tell (#7-8). It happens at idle but also through the RPM range, accel and decel, with 40-45mph in D decel being a particular loud range.

This engine has 239K on it. It’s a well kept engine and clean. On the hottest days with 10w-30, she will hold 22psi oil pressure in drive with 50psi on the road. No knocks and no lifter taps on start up. It does foul #8 every 10K or so and uses about 1 quart of oil every 2000 miles.

It DOES have serious piston slap when cold idle. The cold sound clears up under acceleration and when warm and doesn’t coexist with the noise I first described.

Going to compression check this weekend. It’s been doing this for about a year, getting worse gradually.

I am thinking the piston is very loose back in #7 or 8 and I’m hearing it slap around. Or possibly the precat is loose on that side. Other ideas?

[knucklehead0202]

Possible compression leak from headgasket or perhaps just exhaust manifold? My old Merc blew compression out a headgasket but it sounded like a fuckin' helicopter.

[Tiggie]

It’s not very loud but I’m not ruling anything out.

Couple other thoughts came to me after posting. The sound is similar to what bad wheel bearing sounds like with a little less growl and a little more hollow. I will pull the belt after warming up this weekend to eliminate the accessories. But my wooden stick listening method puts it back in the left rear of the engine.

Considering the bearing like sound, I am trying to think of anything with that type of motion. Roller lifter immenient failure? Piston pin loose (what does that sound like)? It’s due for an oil change this weekend as well so I will look for metal.

[DerekTheGreat]

Run thicker oil in it if you suspect rod or crank bearings. My old '69 318 powered Plymouth would rattle the crank on start-up and flicker the oil pressure light with anything thinner than 50wt oil.

[Tiggie]

Here's a couple videos - still doesn't do the noise justice but it's better than nothing.

Warm - best heard at 15-24 seconds: https://www.youtube.com/watch?v=ViJ-2jmBbtc

Cold - piston slap I think, just for reference: https://youtu.be/5uyrXwAorAw

Lots of alternator and power steering in the background...

[gadget73]

kinda just sounds like loose old motor with typical noisy 80s accessories to me. If its making oil pressure, I wouldn't worry too much about it. Probably the bearings getting a bit sloppy. If the oil pressure is on the low side when hot, that kinda jives with that issue.

[GM_Guy]

Sounds normal to me. Nothing jumped out as being out of the ordinary.

Alex.

[knucklehead0202]

Yeah sounds like loose bottom end. My other '90 sounded like that the whole time i owned it. Put fancy top end shit on it and wound it up more than the average lo-po and it didn't blow up. Of course, it also wasn't alive very long before it got wrecked so who knows...

[Tiggie]

Paranoia i guess... thanks for the reassurance it’s just old and not fatally wounded. I don’t particularly want to launch a rod through the block.

I’d really like to see if I can make it to 300k on the entire drivetrain. I do mostly city driving so the AOD is probably going to be the weakest link. That, or the rear axle bearings. I think it would make it if I did more highway driving.

[DerekTheGreat]

Also, consider the bump to 5w-40 full synthetic with Motorkote additive. After seeing the results on a Project Farm video on an engine running on just that, I'm sold. Reduces wear due to friction and such. That ought to help it go to 300k.

[Tiggie]

Also, consider the bump to 5w-40 full synthetic with Motorkote additive. After seeing the results on a Project Farm video on an engine running on just that, I'm sold. Reduces wear due to friction and such. That ought to help it go to 300k.

I have considered 5W-40. Never heard of the Motorkote but did a little searching and it seems good. First thought was sludge in a can like Restore but it seems quite different. Only 2oz per quart and only once in 4 oil changes.

[DerekTheGreat]

Yeah, I've always seen it on shelves but until some recent videos that came out showing actual results I never bought it. It even helps to quiet power steering pump noise a bit. So far it has been added to the crank case of all vehicles except my Firebird and Ashley's F150.

Restore does increase compression though, Project Farm has another video where he tested that in his old Ford tractor which had low compression in one cylinder, brought it right back up with the other ones. I'd like to know how that stuff works. I put it in my lawn mower and shortly after that, I noticed metal shavings in the oil... Kinda started knocking, and even after changing the oil three times after I'm still seeing shavings, look coppery. Mower was first thing I put Motorkote in and I no longer notice the knocking, still see the shavings, just no knocking.