Leaking trans cooler -- flush transmission?


#1

Back again, with the 1994-ish Volvo 940 with many miles on it. (It’s in El Paso; I’m in MD. A friend gifted this car to my son and his wife for their year in El Paso. Free cars are not.)

Symptoms reported by son: coolant leak near firewall (radiator hoses replaced a few weeks ago); maybe some pressure in cooling system; some oily stuff in the coolant in the radiator.

Shop’s diagnosis: transmission cooler leaking. (Well at least it’s not the head gasket!)

Recommend, for $500: replace radiator (yup!), cap (sure), thermostat (all right, but we get rid of this car in six weeks), and … flush the transmission (alarm!).

Usual advice on this forum is drain and refill tranny, rather than flush. However, seems to me that with high risk of coolant in trans fluid, flush is the right action.

Comments, please.


#2

Yes, flush, but I would suggest dropping the transmission oil pan and changing the filter, too. If the tranny cooler is leaking the oil would go into the coolant when running because the pressure is higher than the cooling system. When parked, the reverse is true and the water will be pushed into the tranny oil. Both are bad, but water in the tranny oil is worse. Replace the radiator/trans cooler, flush and hope the trans is not damaged. Save up for a newer car - good advice anytime you are driving a car that is paid for!


#3

Thanks. Son says $500 is too much to have the car for just one more month. He has two prospective hand-me-down clients – maybe one of them will pick up part of the cost.

He told me the car has 265K miles on it. Certainly getting to the “what’s next” point.


#4

Cost avoidance, $500, Scrap value of car $500, reliable transportation, priceless. Yeah, time to say goodby.


#5

Agree; time to say goodbye!


#6

If the tran fluid hasn’t been changed before in its 265K mile life, then flushing it carries a high risk of dislodging varnish/film buildup - enabling those fragments to end up in the sensitive valve body. In these flushing scenarios, some don’t even make it 10 miles after the flush.