Stinky burnt rubber or exhaust smell coming thru vents...and the solution.

[ImDisaster]

Our '99, with 114K on the ticker, started smelling of burnt rubber or oil. You couldn't see it, but you could really smell it after a few minutes of driving. It was so bad we had to wind down the windows.

I looked all around the engine bay but couldn't find any signs of where the smell was coming from. No oil anywhere. Belts not slipping. Then I put it on jacks and got underneath. I traced my way back along the exhaust looking for a leak but it was leak free. Then I looked under the engine. There was wet oil stains under the transmission and a drop of reddish oil near the edge. It looked like it had been dripping on the exhaust...hence the smell.

I pulled the cover and replaced the old cork seal with a rubber gasket that came with the Wix transmission filter kit. The old cork seal was really stuck on in some places. A putty knife was required to scrape off the old cork. Drained about 5 quarts of oil from the pan and transfer case and refilled. The old oil smelled "off" and was brownish in color.

This seemed to mostly fix the problem but I still caught a whiff occasionally of old burnt oil...perhaps a bit still splashed on exhaust, or maybe the oil was really shot and I was smelling it from the trans vent. I dumped another 5 quarts and refilled and (knock on wood) it has been smell free for a week.

If you are catching a burnt rubber smell perhaps it is time to flush the trans and replace the pan seal.

[pmesfun]

I also had that problem, ended up being the front valve cover gasket. Also am going to replace the pan gasket and filter in my auto tech shop soon. What transmission fluid did you use? I used Castrol Multi-Import Tran. Fluid on the last drain and refill.

[ImDisaster]

Originally Posted by pmesfun

I also had that problem, ended up being the front valve cover gasket. Also am going to replace the pan gasket and filter in my auto tech shop soon. What transmission fluid did you use? I used Castrol Multi-Import Tran. Fluid on the last drain and refill.

I went cheap because I wasn't sure if it was a permanent fix. Flushed with O'Reilly "Global" brand. I'll run it for a while than spring for a full flush and something better...like Castrol synthetic. By pulling the return trans cooler line, it is possible to change 95% of the fluid, vs. the 50% or so, I did, each drain.

[pmesfun]

I sticking to drain an refills until I gradually get all of the old fluid of the transmission. It is possible to damage is by flushing is the transmission hasn't been maintained. I read that Castrol MIV fluid is already a synthetic so that is what I am going to continue to buy.

[ImDisaster]

Originally Posted by pmesfun

I sticking to drain an refills until I gradually get all of the old fluid of the transmission. It is possible to damage is by flushing is the transmission hasn't been maintained. I read that Castrol MIV fluid is already a synthetic so that is what I am going to continue to buy.

I think that is an old mechanic's tale. A typical flush just changes all the oil by pushing it in one side and draining it out the other. That is much more efficient than just changing 5 quarts at a time (how much you get out when you drain from pan and transfer case.

Look at it this way. Lets say the system holds 10 quarts (heard it's more like 12.) A change would yield 50% new fluid and 50% bad. The next change would throw out half of the good fluid you just put in (2 and 1/2 quarts) and yielding 75% good, 25% old. With each drain after that, you throw out more good fluid and get less and less benefit. The next change would dump out 75% good fluid (almost 4 quarts) and leave 87% good fluid...or only a 12% improvement.

[pmesfun]

The drain and refill I did in the summer was the first transmission service other than a flush at 40k(that was 8 years ago). I thought that is not good for the transmission to change out the old fluid completely if it has been in there for some time?