1999 Blazer Transmission Problems
skooterbum
06-13-2015, 12:07 AM
My Blazer has started blowing transmission fluid out the vent now, when pulling my utility trailer. This doesn't happen when I'm not pulling my trailer.
I've noticed this the last two times I pulled the trailer.
I've pulled this trailer all over Iowa with no issues, until now. The back of my Blazer, and the front of my trailer are now getting a nice mist of trans fluid covering them when I go long distances.
About 5,000 miles ago I had the trans serviced, flush / filter / and oil.
The Blazer has the 4.3, with auto trans.
Any ideas why this is happening ??
I've noticed this the last two times I pulled the trailer.
I've pulled this trailer all over Iowa with no issues, until now. The back of my Blazer, and the front of my trailer are now getting a nice mist of trans fluid covering them when I go long distances.
About 5,000 miles ago I had the trans serviced, flush / filter / and oil.
The Blazer has the 4.3, with auto trans.
Any ideas why this is happening ??
Blue Bowtie
06-13-2015, 10:40 AM
Skooter,
Your symptoms can occur when the transmission is overheating. The fact that it does not occur when not towing tends to reinforce that. Slightly overfilling the 4L60E does not usually cause foaming, but grossly overfilling can. However, this would tend to cause oil to vent even when not towing.
Since the transmission was "serviced, flush / filter / and oil" do you know if the trans oil cooler was also flushed? Do you know what oil was used to refill? Was a drain plug installed in the trans oil pan as part of the service?
The 4L60E in your vehicle can use Dexron VI instead of the original fill of Dexron III. The Dex 6 is a semi-synthetic oil which is more viscosity stable and tolerant of heat - To a point.
If there is an oil drain plug, or if you have a large enough catch basin to allow oil pan removal, the pan can be emptied and refilled with about 4-5 quarts of Dex 6 depending upon whether your transmission has the shallow or deep pan. This can help somewhat if the oil used to fill was Dex 3.
It may also be helpful to install an auxiliary trans oil cooler inline with the stock oil cooler in the radiator tank. If the Blazer was built with the factory towing and HD cooling options, it should already have an external trans oil cooler, so verify that is intact, free of debris, and flowing oil.
Your symptoms can occur when the transmission is overheating. The fact that it does not occur when not towing tends to reinforce that. Slightly overfilling the 4L60E does not usually cause foaming, but grossly overfilling can. However, this would tend to cause oil to vent even when not towing.
Since the transmission was "serviced, flush / filter / and oil" do you know if the trans oil cooler was also flushed? Do you know what oil was used to refill? Was a drain plug installed in the trans oil pan as part of the service?
The 4L60E in your vehicle can use Dexron VI instead of the original fill of Dexron III. The Dex 6 is a semi-synthetic oil which is more viscosity stable and tolerant of heat - To a point.
If there is an oil drain plug, or if you have a large enough catch basin to allow oil pan removal, the pan can be emptied and refilled with about 4-5 quarts of Dex 6 depending upon whether your transmission has the shallow or deep pan. This can help somewhat if the oil used to fill was Dex 3.
It may also be helpful to install an auxiliary trans oil cooler inline with the stock oil cooler in the radiator tank. If the Blazer was built with the factory towing and HD cooling options, it should already have an external trans oil cooler, so verify that is intact, free of debris, and flowing oil.
skooterbum
06-13-2015, 01:04 PM
Thanks Blue Bowtie for the info !!
I'm going to print off your reply, take it to my mechanic, and find the answers to your questions.
FWIW, when I had the trans serviced 5 years ago, it was because I hauled two HUGE loads filling my trailer and Blazer, each time totaled 375 miles round trip. After doing this, my trans was messed up. It started shifting real hard, and was winding up a lot more between shifts. The service fixed this, as the trans started working normally again. The trans did not vent any fluid when on these trips though ??
Today I checked the trans fluid, and it was a little over a half quart low. So it has only dropped the half quart + since the service was done.
I'm going to print off your reply, take it to my mechanic, and find the answers to your questions.
FWIW, when I had the trans serviced 5 years ago, it was because I hauled two HUGE loads filling my trailer and Blazer, each time totaled 375 miles round trip. After doing this, my trans was messed up. It started shifting real hard, and was winding up a lot more between shifts. The service fixed this, as the trans started working normally again. The trans did not vent any fluid when on these trips though ??
Today I checked the trans fluid, and it was a little over a half quart low. So it has only dropped the half quart + since the service was done.
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