Automatic transmission growl 1990 240 Wagon

hgshaw · Post by **hgshaw** » 13 Dec 2009, 07:51

Our 1990 wagon 240 has developed a growl at low rpm in the transmission. Fluid level looks ok, but when I remove the fluid check stick, fluid spits back up the filler tube, along with a small amount of smoke (puffs). I'm thinking bad torque converter, but why the back pressure in the filler tube? Plugged vent?

Post by **billofdurham** » 13 Dec 2009, 11:12

Welcome to Matthew's Volvo Site.

Two things can cause the fluid to come out of the dipstick tube:

1. A blocked vent, as you suspect. As the transmission fluid gets hot it expands and the excess air has to go somewhere. Hence the vent. If it is clogged, it will back fluid up the dipstick tube. The vent is not very large and not readily visible from underneath. You have to feel along the top of the transmission to locate it. Never having come across this problem I can't give you any advice on how to clean the vent apart from asking a transmission shop for the best way to check and clear it.

2. A car with automatic transmission has a transmission fluid cooler. It is part of the radiator. If this becomes blocked either externally or internally it can't do its job properly, the fluid heats up, expands and comes out of the filler tube.

Bill.

FCPEURO · Post by **FCPEURO** » 14 Dec 2009, 07:47

Basically, it sounds like this is a big issue. I would check the vent before I would think it is the trans-cooler. The reason I say this is because if you have maintained the transmission correctly, it would be very unlikely that the trans-cooler would have clogged. Where as the vent is exposed to the elements and if you live in a dusty place or a place where is snows, it can get clogged up overtime.

I wish I new how to clean the vent but I would think a pipe cleaner would work. The ones you played with in school that is.

Post by **billofdurham** » 14 Dec 2009, 10:56

it would be very unlikely that the trans-cooler would have clogged.

Having re-read my post I should have put more emphasis on clogged externally, similar to the radiator after summer/autumn when flies, leaves etc. do their utmost to make the system overheat.

Bill.

hgshaw · Post by **hgshaw** » 22 Dec 2009, 09:27

Thanks to all the replies. I'll let you know what I find. Have been away, so only now getting back on it.