When I'm on the freeway, at around 70mph, worst when 80 or 90, I feel a rhythmic pulsing. Yes, not bad for around town, but I want to fix it before I take a roadtrip in case it's serious, and because it's annoying.

It feels like it's in the engine, it's a really "deep" feeling. Deep vibration, pause one second, deep virbation, pause one second.

Any ideas what that could be caused by?

 

my instinct would be driveshaft. You can crawl under and inspect it, or take it somewhere and get it balanced.

I sometimes feel a sort of rhythmic growl from my engine, but I believe it to be the flex a lite fan I installed which is significantly more powerful than the stock. Mine is at idle however.

If it is indeed the driveshaft, you should get that sorted immediately.

 

Diagnose, diagnose... inspect driveshafts, and
I would set the tires pressure different in left and right sides.
If the cadence changes with difference in pressures, I would suspect of wheel bearings.

If you can get tire pressures to a point that the cadence almost goes away or increases badly; same.

Lubricating wheel (hub) bearings can gradually cure it in a few days of driving, if bearings did not reach damage.

 

Do you feel the pulsing in your pants (while sitting in drivers seat) or in your hands (while on steering wheel)? If you are feeling it more in the steering wheel, concentrate on the front end of the drivetrain, if you feel it more in the seat of your pants, concentrate on the rear portion of the drivetrain.

Wheels are usually suspect, when concerns are high speed vibrations or pulsing, especially if you do not hear any grinding or rubbing.

Drive shafts are another suspect, pull each one down and thoroughly inspect the movement and condition of each joint. Look for any signs of rust or rub marks on the joint housing, this will indicate an issue, also.

You may want to check for a brake caliper partially hanging up, this could cause a pulsing situation, also. Jack up each wheel, after driving for a bit, until warm, and spin each wheel...they should move freely.

Good luck,

Brian.

 

Thanks for the solutions guys, great ideas. I will report back once I've tried them.

 

Just fyi, the driveshaft checking is a sooner rather than later thing. Like immediately. If it goes you get a 4" hole in your transmission.

 

The hole in my 01's tranny was six, would this be considered a wall-hanger...lol. Lady I bought it from said she was traveling at highway speeds when it went. Besides the transmission issue, you'll most likely need a cross over pipe, too.

Anyhow, another good routine for finding a vibration in your drive train...is changing your fluids and looking for any signs of excessively worn parts in the pan or on the magnetic drain plug. Especially, if the vehicle has over 100k and has never been changed. Axles and transfer case get looked over on these vehicles, so changing the fluid (and inspecting) is a good maintenence practice.

Forgot to mention, while you have the rover jacked up...grab each wheel at the top and bottom, front and rear...and wiggle. There should be no movement, if hubs are in good working order. Now, l've seen plenty of bad hubs that had no movement at all...but in those cases...usually they gave away there issues by making noise while spinning wheel (with caliper removed).

Another thing, while you have the wheels in the air, spin each tire, while looking at the vertical grooves in the tire thread pattern, look for any "shifting" of the groove while spinning tire. This usually means you have a broken belt inside the tire...and that will cause issues like you've described.

Brian.

 

Simple thing that can get overlooked: Get your wheels balanced. If you threw a weight or similar it can give you that kind of symptom.