Well, I’ll try to make this as short as possible. Vehicle is a 2001 Dodge Grand Caravan, 3.3L V6, 100k miles.
Van was towed to the shop after overheating on the highway (pulled over and turned it off before it hit the red on the temp gauge). A coolant leak was fixed and the rear drums/shoes/wheel cylinders were replaced (cylinders were leaking and the rear brakes were overdue).
Immediately after this service, the van would shake/vibrate at highway speeds. It was fine at lower speeds. The winter rims&tires were on at the time, and I recently put the regular rims/tires back on. No change in the vibration!
Today, I went to have a slow leak fixed on one of the tires, and had them also rebalance all the tires. This helped, but very little, and I’ve noticed recently that it shakes at low speeds too (35/45 mph). I noticed it especially today when I was reducing my speed into a neighborhood and was off the gas and brakes, and the rear seats were shaking.
What could cause this kind of vibration? I can’t see anything the shop did that would cause this, could the tow have damaged something?
Thanks for any suggestions, let me know if anything needs to be clarified, I tried to give you the “Coles notes” version.
Jad
Oh, and the tire shop thinks the alignment is good from looking at the wear on the tires.
find a long straight road, (preferably without much traffic)
get it up to the upper end of speed, put it in Neutral (not OFF, but neutral, key on). let it coast down through the speed range you are concerned with.
see if this changes the vibes.
this should help figure out if this is a drive line or a tire problem.
i would suspect a broken rear spring, shock, or mount on the axle if the tow was hard on the van. have you followed (or had someone follow you) and watch the different wheels for vibration, jumping?
does applying the brakes change the vibes? (or having the brakes on, then releasing them?)
Might want to have your mechanic use the machine to check your alignment rather than gauging it by visual evidence of tire wear since you mentioned changing out your winter rims/tires for regulars recently. If your alignment is bad (assuming you haven’t driven it a great deal since the tow and the car repairs) it’s unlikely your tires would show much wear, yet. If it is a bad alignment, the mal-wear will come with time.
I would also check all of the mounts. If none have been replaced yet, 100K isn’t a bad number for them to show some wear, and the extra torquing from the two may have pushed one or two over the edge.
I tried the neutral coast-down test and it didn’t change anything.
Haven’t had any one follow the van, I’m surprised it would be visible to the eye, but I’ll try it!
Braking doesn’t change anything, and the pedal feels smooth, too.
Are we talking about motor mounts?
That’s a good point, I’ll get that checked out.
Motor and transmission, but now I’d be less likely suspect that since that the vibration doesn’t change in neutral. A mount problem might be felt while coasting, but it would normally be tied pretty clearly to acceleration and should calm noticeably if you coast.
Aside from that I misread the initial post (space cadet) thinking that the tow reference was to you having towed something - sorry 'bout that (though it wouldn’t be a strange time to start having mount troubles).
Do you trust this shop? I will second the alignment check - but I also wonder if the shop didn’t do something weird like drop it off a lift. There also could have been a tow truck mishap, but problems from either of those things should show up during alignment.
No, while I appreciate what you’re saying, the shop is owned by good friends of mine. They would be honest about anything like that.
I hope it’s just an alignment issue…but I’ve always thought alignment issues only cause a pull to the left or right, not vibration? Is that incorrect?
Hopefully someone with more expertise than I can answer better - your issue does sound a lot more like a tire/rim issue than alignment but since you swapped those and nothing changed that seems unlikely.
Poor alignment can involve more than just pull, and you’ll never really lose by having it checked. Part of the bonus though is that alignment often reveals problems with general suspension and steering issues. At this point I’d be asking for a once over of front and rear suspension/steering and alignment check.
Depending on the skill of the tow-truck driver, they could have damaged your axles. They are supposed to connect to the front crossmember, but I have seen some get lazy and hook the chains to the axles. I’d have somebody check the cv-joints and axles.
Thanks, silvergc1. That’s what I was afraid of. I’ll get the CV joints and axles checked out when it goes back to the shop on Monday.
UPDATE
Well I got the van back today after my mechanic checked it all out, and had taken it home to really get a feel for the shake/vibration. He said they looked over all the suspension and steering components and everything looks good/checks out, and they really went over it all. The only thing they found was that the tires were out-of-round, even though they would balance on the machine.
Now, they are older tires, mismatched brands front/back, but they were fine before. This also doesn’t explain why my other set of wheels and winter tires were doing the same shake/vibration. Mechanic can’t explain it either, but thinks a set of new tires is the fix (and I know he’s not just trying to sell me tires).
Any ideas? I’m really confused and this shake is really annoying. Again, the problem areas are 35-45 mph and then 60mph and up.
ALL WHEEL DRIVE? or front wheeel drive?
Front wheel only.
For anyone who’s following this, I had an idea to possibly verify this diagnosis.
I have a good relationship with a tire store that sells new and used tires, and I’m thinking of asking them to throw on 4 decent used tires and then let me take the van for a spin. I’ll know very quickly if the tires have solved the shaking problem. If it doesn’t, I’ll pre-arrange with them to pay something like $40 to put the old ones back on and take back their used tires. And then try to find out the real problem.
Sound like a good plan?
One more idea:
Have someone in another vehicle drive beside you and look to see if any wheel appears to wobble.
One other test is to swap the front and rear tires and wheels. If the shake now is in the front, you know the problem is in the tires and wheels.
Depending on the skill of the tow-truck driver, they could have damaged your axles. They are supposed to connect to the front crossmember, but I have seen some get lazy and hook the chains to the axles. I’d have somebody check the cv-joints and axles.
This was my first thought also. If a CV joint was damaged, it won’t necessarily be obvious upon inspection. The boot will cover the evidence.