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Old_Crow · 05-10-2018, 05:51 AM

Coach is an '00 Bounder 36S on an F53 chassis.
Engine runs fine, no SES light or unusual gauge readings. When accelerating onto a freeway I pick up a fairly heavy vibration between about 50-60 mph. Once highway speed has been reached it seems to go away. I normally cruise at about 62-63, so basically the vibration starts about 50 and continues until I let off at my set cruising speed. If I come to a hill, as the coach slows into that 50-60 mph range the vibration comes back. Above and below that speed range everything seems fine, even at full throttle acceleration.
I've been under the coach and I don't believe there's any unusual play in the driveshaft support bearings or U-joints.
It also doesn't seem to make any difference if I lock out the overdrive on the transmission(was thinking maybe converter?). Frankly, I'm out of ideas.
Anyone here had something similar and solved it?

twinboat · 05-10-2018, 06:02 AM

Did you chock the wheels and put the trans in neutral, parking brake off, while checking the drive train ?

Drive shaft slip joints can wear. Any slop will cause vibration at different times. U joints can seize causing vibrations. Any powdered rust near a U joint is bad.

Failing support bearings can cause vibration too. A quick test would be to feel for heat in it after a drive.

If the drive train looks tight, I would suspect a failing ignition coil. I believe there are some code readers that will ID which one.

Craig1960 · 05-10-2018, 06:12 AM

It sounds like a driveshaft problem for sure. Usually it will be at a certain speed range like you described and you will feel it in your seat apposed to in the steering wheel.

hbrandon · 05-10-2018, 06:15 AM

What brand shocks are you running?

Old_Crow · 05-10-2018, 10:48 AM

Twinboat, you might have something there. I haven't seen the check engine light come on at all, but after your post I hooked up the code reader and lo and behold I had codes for misfires on #'s 3, 5 and 7. Cleared the codes and ran the engine but no codes reappeared. Apparently they only appear under load.
Due to some medical issues it's going to be several months before we move the coach. Guess I'll put this on the back burner until shortly before then.
Sure glad no one piped in with some obscure transmission problem that would have caused a boat load of cash. I'd way rather change a couple of coils than that.
I might even get a set of plugs and throw in there, just cause I've only had the coach a year and I don't really know the history.

Bob Hyatt · 05-10-2018, 12:50 PM

Quote:

Originally Posted by Old_Crow

Twinboat, you might have something there. I haven't seen the check engine light come on at all, but after your post I hooked up the code reader and lo and behold I had codes for misfires on #'s 3, 5 and 7. Cleared the codes and ran the engine but no codes reappeared. Apparently they only appear under load.
Due to some medical issues it's going to be several months before we move the coach. Guess I'll put this on the back burner until shortly before then.
Sure glad no one piped in with some obscure transmission problem that would have caused a boat load of cash. I'd way rather change a couple of coils than that.
I might even get a set of plugs and throw in there, just cause I've only had the coach a year and I don't really know the history.

If it sits idle for long periods of time, might be a fuel problem as well. And that will cause never-ending random cylinder misfires until things are cleaned out. Diesel - not so bad although it doesn't like sitting either. But gas? ethanol and phase-separation are a royal pain for gas that sits a month or longer in the right kinds of humid conditions.

Old_Crow · 05-10-2018, 08:31 PM

This actually started last fall on the way home from our host job at the Grand Canyon. Over the winter I've put almost 2000 miles on it following my wife around to different hospitals, so it hasn't sat all that long. I knew last week I'd be sitting for a while this time, so I filled the tank(which was below 1/4 tank)before I hit the campground, hoping to minimize condensation build up in the tank. I also dumped a quart of Stabil in the tank while I was filling it.
I think I'll crawl under it again and re-check the support bearings and u-joints(coach has less than 40k miles on it)and swap out the plugs some time this summer. Then, when the docs release my wife I'll hook up the scanner and take us for a ride to see if the misfires come back.
Truth be told, if the thing had a distributor and plug wires(giving my age away here), that's where I'd have been looking in the first place, so a bad coil wouldn't be a big surprise.

Waiter21 · 05-10-2018, 09:36 PM

Ford issued a TSB for 1999, 2000 F53s relating to a vibration at certain speeds.

The main culprit is the wheels (rims) do not center precisely on the axle hubs. I had this problem on my 1999, I'd get a funny vibration between 50 and 55 mph.. The cure was to use the centering sleeves when installing the rims. This cured the vibration and its now as smooth as glass..

TeJay and I did some very precise measurements on our rims, the lug holes on mine (1999) were a little larger in diameter than his (2014) .. The larger diameter holes allowed the wheels to be mounted slightly off center. The sleeves basically reduce the hole size during installation and force the rims to be centered. I believe Ford reduced the rim lug hole diameter mid year 2000, so this is no longer a problem after mid 2000.

Inexpensive sleeves can be bought for about $45. these are used when mounting the rims, then removed. You can see how I used the sleeves when installing the front tire. I used them also when installing the dullies.. You can read my article and there is also a link to the TSB.

Funny vibration around 50 mph – Wheel Centering on F53 – 1999 Southwind 35S

..

Old_Crow · 05-12-2018, 05:51 AM

Waiter, I read your write-up, and the TSB in the link. I don't think this is my vibration, because I don't really feel it in the steering wheel as stated in the TSB. Seems more like it's driveline related or a misfire under load as others have stated.
Thanks for the post though. Gives me something else to watch for in 3 pr 4 years when it's time for tires.

TeJay · 05-12-2018, 07:07 AM

Wally,

Waiter21 brought up a very good point as he alluded to. You sound like you've got some mechanical experience so don't do as many have done and jump to conclusions. I've been down this road before on several poster threads with vibrations that occur at specific speed ranges.

You remember coils, coils wires, distributors. Those secondary circuit insulation break down almost always occurred when under load and not at specific speeds. That's just the nature of it. The insulation around the high voltage secondary is sufficient until under load the output goes up and the insulation breaks down.

Yes because of the age of the RV you may still have secondary breakdown issues but I'm still thinking you have a vibration specific to a speed of rotation namely between 50 and 60 MPH.

If after you reach 62 to 65 MPH you get no vibration. What happens if you accelerate to 70 or 72 MPH?? If it's insulation break down then it should vibrate again. It's again under load so why not.

My guess is no vibration. If you did have more vibration under load going from 62 to 70 then yes ignition break down. If you have no vibration then it has to be a vibration related to an off balance tire or rim, maybe the DS or some other rotating part that vibrates based on the rotating speed and not a load situation. My guess is the rims are off center.

I'm just trying to follow the symptoms as created by the OP. Follow the correct paths of the troubleshooting symptoms. JMHO

Waiter21 · 05-12-2018, 04:19 PM

Old Crow. No problem. Could be bad balance on wheels/tires. If the rears are out more than the fronts you may not fell it in the steering wheel...

If you take it somewhere to get the tires / wheels inspected or balanced, make sure they use the sleeves when they re-install the rims on the axles, its the only way to guarantee they are centered.

I keep the sleeves in my tool box in case the tire shop doesn't have any.

Old_Crow · 06-14-2018, 01:45 PM

Okay, been a while, but I finally got this thing out on the road and drove it a few hundred miles. It's definitely missing under a load. Got a code reader and I'm getting random misfire codes from pretty much every cylinder. You can clear the codes and it'll come back a different set of cylinders in a few miles.

I've run like 3 tanks through it in the last 3 days and it seems to be getting a bit better. I may invest in a fuel filter and a couple of bottles of injector cleaner to dump in the tank before I do the filter.

Anyway, I'll mess with it later, after I get my stupid oil leak fixed.

The up side of the whole thing is, it's been averaging 6.5 mpg pulling the Jeep. Think how much better it'll get running on all 10!

expo · 07-10-2018, 10:40 PM

Check your front tires to see if they say MADE IN CHINA. (Good-Ride, Roadmaster are a few) They are known for going out of round causing vibration at certain speeds regardless if they balance true.