Engine squeak/squeal

[rwilliam99]

My son has a 1969 F100 with the 300 straight 6 in it. It runs really well, however there is one item that we can't figure out. When we bought it in the summer, it ran great with no noises, but on the way home (after about 20 minutes of driving), it started squeaking/squealing. We figured it was a loose belt. We replaced the belt and have tightened it up but the squeak/squeal continues. We also checked the water pump and alternator and neither of those seem to be failing (neither is loose or rough when turned by hand). There is a slight oil leak from the valve cover gasket and one idea was that the oil was getting on the belt and causing it to slip.

Does anyone have any other good ideas on what might be causing this? It seems to be worse now when it is colder (in the mornings), but does seems to be getting more consistent as time goes on.

Thanks much for any help you can provide.

Rob

P.S. - I learned something new about timing - The "time by vacuum" method that has been described here. His truck runs a LOT better when it is timed that way, rather than timed to factory specs.

[ToughOldFord]

Pull the belt off and start it. If the noise is gone then it's alternator or water pump. Usually it's the alternator. (In my case anyway. )

[Fordlorn]

I had a rocker rub on a valve cover that sounded kinda like a squeal/squeak. It took forever to figure it out! I would have never suspected it until a buddy told me to look at the valve covers. The rocker just barely was touching the breather baffle in the cover. Was kinda scrubbing the flat surface of the baffle hanging down. Was a nice little bright spot where it was rubbing. Took a hammer to it and "Viola" quiet!

[rwilliam99]

Pull the belt off and start it. If the noise is gone then it's alternator or water pump. Usually it's the alternator. (In my case anyway. )

Since it doesn't squeak all the time, this will be the challenge. It seems to do it when he comes home from work/school, so maybe we can do it right when get gets home.

Is there any other way to find out if the bearings in the alternator are going? I've always just spun it, and if they were going you could usually tell pretty easily. His alternator spins pretty freely.

Thanks for the ideas. We will try some of them out this weekend.

Rob

[rwilliam99]

I had a rocker rub on a valve cover that sounded kinda like a squeal/squeak. It took forever to figure it out! I would have never suspected it until a buddy told me to look at the valve covers. The rocker just barely was touching the breather baffle in the cover. Was kinda scrubbing the flat surface of the baffle hanging down. Was a nice little bright spot where it was rubbing. Took a hammer to it and "Viola" quiet!

He had the valve cover off (he had to re-paint it to make it look nice ), and I don't remember seeing any spots on the underside. He needs to replace the valve cover gasket anyway, so we will look at this as well.

Rob

[fordman]

you could try just loosening the belt a slight. maybe its way to tight. another way to check the alt bearing is in its up and down pulley shaft play or maybe in and out play.

[rwilliam99]

Well, when my son came home on Friday, the squeak was there, so we quickly removed the belt and started it back up and the squeak disappeared, so we spent a frustrating weekend replacing both the water pump and alternator. It appeared as though the alternator bearings had some excessive end play which might have been the squeak. Had to get two water pumps, since the first one was "almost" correct (not quite tall enough, so the pulley bottomed out). My son went to school this morning, and he calls me when get gets there and tells me the battery is dead and the squeak is back....Ugh...It appears we didn't do something right with the alternator (or it is bad).

Is is possible this squeak/squeal is a spun bearing that only spins after the engine warms up? Anyone have any other ideas on what it might be?

Thanks for all the suggestions....

Rob

[BZinAZ]

Squeaks and squeals - Never fun when you keep throwing parts at it... I have found that a good method (when the sound is present) is to use a mechanics stethoscope. It's just like a doctors, but has a metal probe instead of the round/flat end. You can get them at Harbor Freight for under $20. Probe around with that and you should get to the bottom of the issue. But if it goes away with the belt removed, it seems like the front end accessories.

A spun bearing can squeal (I know from experience- ouch!). How is the oil pressure at start-up versus warm? Have you found any metal silt in the bottom of the oil pan? Is there any knocking at start-up?

What type of fan is on the motor? If it's a clutch fan, it could surely squeal...

Good Luck

[rwilliam99]

No clutch fan, so that doesn't seem to be it. I swear we heard the squeak/squeal while sitting in the garage, but my son isn't sure. One of his friends thought it might be something in the drive train, but if it does it standing still, I doubt that would be the culprit (other than the throwout bearing).

He will check the oil pressure tomorrow morning when it is cold, but he didn't see any shavings in the oil when he changed it, and there is no pronounced knock on startup.

What should a "normal" oil pressure be for one of these engines? When warm, it runs about 30-35 psi according to the aftermarket gauge that someone put in it.

Thanks for the response. This is a rather frustrating problem....

[rwilliam99]

OK, some more info:

We fixed the alternator issue - I hate to admit it, but it was a stupid mistake on my part. I hooked up the alternator wiring wrong! Anyway, I hooked it up correctly, and it appears to be functioning OK now. I was afraid I fried it, but it seems to be OK. The water pump and valve cover gasket are not leaking, so that looks good, too.

Oil Pressures:
Oil pressure when cold (idle) - about 40 psi
Oil pressure when warm (idle) - about 20 psi
Oil pressure maxes out around 35 psi or so when warm.

From what I've been able to gather reading some other posts, that oil pressure doesn't sound too bad.

Although I swear we heard the squeak/squeal when the truck was stopped, my son says it is only when moving, which now makes me think it is something in the drivetrain. He says when he slows down and stops, it will continue to squeak for a second or so after stopping, but then stops until he starts moving again. Could that be the throwout bearing? That is the only thing I could think of that would still be spinning after stopping...

Anyone have any other ideas on what to check? I have a friend that has one of those stethescopes, so I may try that as well....

[fordman]

i have heard ujoint squeal when you take off but not as you are coming to a stop. they might clank if you came to a stop. or maybe he is hearing the disc brakes sqeal. if he has them i mean.

[rwilliam99]

i have heard ujoint squeal when you take off but not as you are coming to a stop. they might clank if you came to a stop. or maybe he is hearing the disc brakes sqeal. if he has them i mean.

No disk brakes on this truck....Everything is old school and manual.

I'm thinking maybe it is time to take it to a pro....I've got a friend who swears by a mechanic he uses who is great at diagnosing problems. I'm pretty sure I could fix it, if I knew what the problem was, and I hate to keep throwing parts at it.

Thanks for the suggestions. If anyone has any other ideas, please let me know. If I find the solution, I will post it here. Maybe it will help someone else.

[BZinAZ]

My experience with throw-out bearings is that they tend to "whirrr" instead of squeal, but one way to help isolate is to ask your son if the squeal (while moving) is affected by pushing in on the clutch pedal. If that's not it - my next step would be to get 4 heavy duty jackstands and put all 4 tires in the air (with the truck pointed in a safe direction of course) and listen to the tranny/driveline with the tires spinning. Did your son happen to mention at what speed or RPM this squeal presents itself?

[rwilliam99]

My experience with throw-out bearings is that they tend to "whirrr" instead of squeal, but one way to help isolate is to ask your son if the squeal (while moving) is affected by pushing in on the clutch pedal. If that's not it - my next step would be to get 4 heavy duty jackstands and put all 4 tires in the air (with the truck pointed in a safe direction of course) and listen to the tranny/driveline with the tires spinning. Did your son happen to mention at what speed or RPM this squeal presents itself?

UPDATED BASED ON A CONVERSATION WITH MY SON TONIGHT:

That has been my experience with throwout bearings as well. I asked him the question about when the clutch is depressed, and he thought it might make it a little quieter, but not much. I think maybe I'll try and drive it when it warms up and squeals and see what I see/hear/feel, and maybe that will give me more clues. This has been a real learning experience for him, learning to listen to the vehicle and see what it tells you.

The squeal seems to happen more at higher speeds (he says above 40), but it is more pronounced (I think) under a constant load. If you press the gas down harder (hard load), the squeal gets quieter or goes away.

I've never removed a tranny from a truck, but I'm guessing it will be pretty heavy, and I'll need a tranny jack. Sounds like a whole day job to me, and I really don't feel like doing that for nothing.... And I don't have 4 jackstands that I'd trust to run the truck on, but maybe I could borrow some.

The saga continues....I'll post more when I know more.

[rwilliam99]

Well, I have more info. I took his truck for a test drive this afternoon. It is even weirder than I thought....

First, the truck has to be warmed up. Next, you have to be driving about 40mph or more in 3rd gear. You then hear the squeal/squeak. It isn't too loud, but it is definitely audible. If you press the gas hard, it will either get much quieter or go away completely. I tried downshifting to 2nd to see if it happened in 2nd, but I couldn't make it happen. My son says it sometimes happens in 2nd as well, so it sounds like it is happening in a certain RPM band. Since he doesn't have a tach on the truck, I'm not sure what that is. Pressing in the clutch has no effect whatsoever on the sound. In listening to the noise closely, it almost sounds like it could be some sort of vacuum issue. A leak when the vacuum gets too high? The PCV valve chattering? Unless someone here has other ideas on what to check, I think I'll contact the local mechanic and see what he thinks...

Thanks for all the suggestions.