1990 vibration

[Cdnrunner]

Hi all;

I have a 1990 4 runner with a V6 and a std tranni. Lately I have begun to experience a vibration when the engine is under load driving down the road. (almost like it's missing on 1 cyl). If the engine is idling or I put the clutch in while moving there seems to be no problem. I have changed the plugs, cap, rotor and checked all the wires for resistance. No luck. The vaccum is good and the fuel filter is new. Could this possibly be a driveshaft or u-joint problem? I haven't had an alignment done but then again the truck does not pull to one side at all. The last repairs I did was to change the front shocks, the front sway bar links and put the summer tires back on. (they are only 235s) Any thoughts??

thanks in advance.

[Brian R.]

Hey - Welcome to the 4Runner forum!

Could be your injectors are dirty. Try putting some Chevron (or equivalent) fuel additive in a tank of gas and see if that has any effect.

[magnor]

I had a 1990 and the vibration started as I got up to 35-45 MPH. Had it checked, it was a small Transmission "rubber mounting". Was inexpensive as I recall (including labor was $150. approx). From age, the rubber had started to deteriorate and hence, the vibration. Hope this helps!

[GRIMRUNNER]

check your u-joints at the rear diff, I had a similar problem and that's what it was

[Cdnrunner]

Thanks all!! It was indeed the rear U-joint although it sure looked ok on the last grease job. When I took it off it darn near fell apart.

Going for a couple thousand click trip towing a 3000lb trailer next week, I'll let you know how it works out.