[zukmeista]

If I change gear from 3rd to 4th at anything lower than about 3500rpm, I get really bad vibrations that sound like they are coming from the engine

[royce]

do you get a rattle sound? probably pinging, put better fuel in and check your timing

[zukmeista]

The engine rattles a little bit but I use the highest octane fuel I can get (usually 95). The motor has also been tuned a couple of months ago so I don't see how the timing could be out after a couple of months? Timing belt was replaced at 96,000 k's and the truck has done about 14,000 k's since then

[foonji]

are you going up a steep hill when making the change?

[zukmeista]

Nope... This happens when I am on flat ground doing less than 3500rpm in third and then change to fourth gear. It is annoying because I generally take it pretty easy in my truck and I try to avoid revving it past 3000rpm if I can help it.

[steak_knife]

4th gear syncro's by the sound of it, is it hard to get into gear when this "vibration" is happening???

[zukmeista]

Nope, it slots into gear perfectly. I wouldn't think the syncros would be worn after only 108,000kms though

[PJ.zook]

Can you hear the general area of the vibration? Does it rattle the hell out of anything or just a noise? Can you feel it through the steering jerking the car about?

On a side note, assuming its a 1.3 sierra, do give it a good thrashing every now and then, its good for the carby.

[zukmeista]

The vehicle is an '89 1.3 G13A. The vibrations are quite bad and seem to come from the engine. I do give it a bootfull in 2nd gear to 60km/h occasionally but the previous owner probably wouldn't have revved it past 3000rpm.

[steak_knife]

zukmeista wrote:

Nope, it slots into gear perfectly. I wouldn't think the syncros would be worn after only 108,000kms though

I've replaced syncro's at 25k on Jim's

[zukmeista]

Any other ideas then?

[nath_89]

ive got the same problem with my 92 1.3 im no mechanic but i rekon its sounds/feels like the g/box dunno?

[PJ.zook]

Try and start isolating the vibration. Put smaller road tyres on it, see if that does anything.
Then start with driving along a safe road, get it to vibrate, then see if vibration is still there with clutch in, or when gbox in neutral, transfer in neutral, etc...

[Scrawny]

Check engine and gearbox mounts. Check for play in diff pinions, transfer and all uj's. Check for play in steering, suspension bushes and wheel bearings.

I'm picking it's a uj or transfer/pinion bearing.

[jimbo_jones]

Could be a uni like the lwb on eBay Jack shaft let go and made a good hole in the tunnel

[zukmeista]

But it only does it in 4th gear???

[jimbo_jones]

zukmeista wrote:

But it only does it in 4th gear???

do it only do it in 4th at a cetain speed or will ts do it in 3rd at higher revs or in 5th at lower revs ?

[nath_89]

mine only does it in 3 or 4th when i give it a bit

[Scrawny]

zukmeista wrote:

But it only does it in 4th gear???

4th gear is a direct drive through the gearbox, it may be a bearing problem in the box

[zukmeista]

Oh... What should I do about it?

[Scrawny]

Check the rest out before you condemn the gearbox