80banana

My truck has a pretty noticeable engine vibration that I'd like to try and correct. It's an 80 20R with about 248k miles (burns a little oil, but doesn't leak) and has had this vibration since I've owned it. It doesn't appear to be affecting power nor does it appear to be a fuel or ignition system problem, but rather than wait and let it get worse, I'd like to figure out what's going on. The vibration doesn't appear to be coming from the drive line, as it can be reproduced while revving the engine while the truck is at rest. Below 2k rpms, the engine sounds normal, but around 2500 or so, there's a noticeable vibration that gets louder and stronger up into the 3k range. It doesn't sound like a metallic or knocking noise, but more like a lack of insulation between two metal components, like the frame and the body or the engine and the frame...something like that. It's hard to describe, but I plan to take a video to try and capture the noise. Inside the cab, you can watch the steering wheel and dash vibrate slightly while the engine is revved into the vibration range. The vibration appears to be louder on the driver's side than in the passenger area. Some things that were recently done within the last few thousand miles: new transmission mount from Toyota, valve adjustment, water pump, fan clutch, plugs, rotor, cap, crank pulley and all drive belts. I've considered that it may be the motor mounts, but I'm not really sure how to check them. Anyone have any other ideas on things to check? Thanks

the_supernerd

The quickest way to check the motor mounts is to have someone let the clutch out in both 1st gear and reverse while you watch the engine. If it appears to lift up significantly in one direction or the other, the mounts are probably bad. In a couple of trucks I have been in with bad mounts, I notice the gear shift moves quite a bit while doing a hard take-off from a complete stop.

Another thing to check is the timing and make sure the mechanical and vacuum advance in the distributor are both functioning properly. Sometimes if the wing nut on my air cleaner housing is not tight enough it can create a small vibration. Also check all of the heat shields on the engine to make sure none of the bolts have loosened.

toyotabull

You said a new crank pulley? What about your harmonic balancer? Either that or a motor mount comes to mind.

truckman1966

I was thinking balancer or motor mount. but a motor mount wouldn't cause a resting, non-moving vibration. would have to be something with the engine itself. if you put the clutch in, does it go away or does it do it both engaged and disengaged? take a look at the balancer and check the condition of the rubber in between the hub and ring. if the ring on the outside has moved in any way, or the rubber looks like it is coming apart, cracking, torn, missing, etc. there's your girl. have you checked your plugs? oil fouling will cause a nasty miss in some cases. hope that helps

traveljoe

I have the same vibration that instantly started after running over a dead bear on I-5. I think it's my motor mounts. I'll keep checking back and I'll let you know if I am able to fix mine.

truckman1966

I wonder if banana figured it out and just withholding info!!!!

traveljoe

I looked at my engine mounts and one of them had completely separated. It looks pretty ugly. I'm going to get some polyurathane ones from LC Engineering.

truckman1966

if you are doing polyurethane engine mounts, you should get a trans mount too

80banana

Sorry all! The brake master cylinder seal went out and I've been preoccupied with replacing that and bleeding the brakes.

Anyway, I was under the impression that the crank pulley and harmonic balancer are one in the same on this 20R...is that correct? In any event, that part was brand new, has a good rubber insulator between the hub and the ring and replacing it did nothing for the vibration, although it did stop a pesky oil leak (along with a new oil seal). The resonating noise happens both when the clutch pedal is pressed or released.

80banana

One thing that just came to mind was the body mounts....I wonder if that's what is causing this resonating noise? The noise seems to be loudest while in the cab, but if I stand outside and rev the engine, the noise is still noticeable and appears to be coming from the top end of the engine (listening to it with a mechanic's stethescope).

stokesdead

ever take a look at those body mounts? Im interested in what you found.

traveljoe

I just replaced my engine mounts with some LC Engineering polyurathane mounts. It took me way to long to install them and I had to file the holes quite a lot on both because the width wasn't quite right. The engine doesn't jump around anymore (my old mounts were toast), but I still have a loud harmonic hum that is worse at lower rpms. Not sure what to do. Where is the harmonic balance on the 22R engines?

truckman1966

i kinda figured it wasn't the motor mounts. traveljoe, the balancer is on the front of the crank under the water pump. banana, is it a heat shield on your exhaust mani? maybe a cracked manifold? that is common. is it a resonant rattle?

80banana

Hi all, sorry for the delay. I took some videos but I cannot figure out how to get them off my camera and onto the computer. I may have to borrow a newer camera with an SD card in order to do that.

Yes, I looked at the body mounts. While they definitely look their age, they appear to be physically intact in the front of the truck. I also looked at the two engine mounts and from what I can see (limited by other things in the way) they look to be in similar shape. I have a feeling that the resonating noise is not being caused by failed mounts or rubber.

After close inspection of the exhaust manifold heat shield, it appears that it is vibrating during deceleration or if I slowly accelerate the engine, almost as if something is loose. If I place my hand on the heat shield (using a glove, before the engine warms up), I can press the heat shield slightly against the manifold which will alter the noise and somewhat quiet the noise. All the bolts holding the shells of the heat shield appear to be tight. At this point, I'll be focusing my attention on this area of the engine as I have a feeling that this is where the noise is coming from.

I didn't realize that these engines had a problem with cracking exhaust manifolds. I'll have to pull the heat shield off and check the manifold for cracks. Where should I be looking on the manifold or where do they usually crack? Thanks for that information.

If I determine that the manifold is cracked, well then, I guess I'll need to find a new manifold. If it's not cracked or damaged, maybe I'll try running it with the heat shield off and see how it sounds. Might as well get a gasket set before I pull all that mess off.

I'll try to keep you all posted as I move forward. Thanks

traveljoe

I took another close look and listen at the engine since replacing my engine mounts. It really doesn't seem like my engine is where the vibration is originating from, unless it is being amplified greatly by something else. I can't feel the vibration on the engine, but the body all over the truck is vibrating very much. When I begin increasing the throttle and when I first let off of it the noise and vibration gets peaks. My whole exhaust pipe is quite rusted, with holes after the muffler. The muffler itself rattles on the pipes at both ends and it appears to be developing a rust hole that while be about as big as a dime when it gets all the way through. I have thought that when I hit the bear, the impact may have jarred the baffles loose. Does this sound like it could cause such an intense body vibration? Either way, I think we're making progress toward a solution, banana. Best of luck.

traveljoe

I took my truck to an exhaust shop to have them look at it. Within 5 minutes they were able to tell me that my whole exhaust system was shot. They said that there is just a slight leak at the manifold, not a crack though. Other than that my catalytic converter is bad and I was right about the baffles in my muffler being jarred loose. The exhaust inspection was free by the way. I would have that checked out on yours, Banana. I'm pretty confident that I found my problem. I'll let you know when I fix it.

80banana

Thanks for your feedback and suggestions. Work and home life have been robbing my free time lately, but I'm anticipating having some free time soon to continue diagnosing this vibration. Apologies for my delayed responses.

I'll definitely have to have the exhaust system checked out, per your suggestion; can't go wrong if it's free! To my eye, the exhaust appears to be solid, but it looks like it was a custom job that was made to look OEM.

I was going through some old maintenance records and it appears that the exhaust manifold has been resurfaced and repaired at one point. I'm not sure what was "repaired", but I'm curious so I will have to pull the manifold off to take a look. Maybe it has a crack, like traveljoe mentioned.

Whatever the cause is, I'm pretty confident that it's coming from somewhere under the hood. I'll post back after I have a look.

JustDSM

Quite interesting thread. Just last night I finally got my pickup back on the road after a header I ordered didn't fit.

I've noticed that the cab resonates quite a bit more than what I think is normal or even acceptable since this truck is to be my daily driver. I installed some LC Engineering Poly mounts like traveljoe, and initially thought that might have been the cause. The mounts are noticeably stiffer, and I expected them to transmit a little more NHV into the cab.

Previously the header was cracked and leaking so it had a pretty loud exaust leak which I'm guessing masked this resonating sound. I've got the entire cab/doors of my truck lined with a "Dynamat" material and it's keeping the pannels from physically vibrating against each other, but the deep low frequency tone of this vibration is a bit of a worry to me. While driving last night, I shut the truck off and just coasted and it coasts just fine, zero noise/vibration from the axles or anything.. But the instant the engine was restarted the vibration resumed.. So I'm confident that it's engine related.

I'm planning to check out the harmonic balancer when I get home this evening. The engine was recently rebuilt within probably 10-20K miles. It was a remanufactured longblock and just made a 1200mi trip from North California to Southeast New Mexico without issue. I'm confident that the motor is in good health.. I just wonder how it was balanced..

Gov't Mule

Based on your description, my money is on a bad water pump OR a bad fan clutch. Keep us posted...

JustDSM

I had not thought of those things being the culprit. I'll give them a look this evening never the less! Thanks for your input!

Might I ask, what leads you to believe it may be those two items?