1997 Bonneville SE quirks
07-27-2005, 02:36 PM
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1997 Bonneville SE quirks
I bought a 1997 Bonneville with over 151,000 miles over the winter. As the weather warmed up here in Alabama, I started to notice the transmission (4T65E) cycling between 4th and 3rd gear going up a moderate hill. I also noticed that the transmission shifts kind of hard into 3rd and 4th when it is hot. The fluid has around 7,000 miles on it and looks good. I swapped the themostat to a 180 degree and it seems to have helped. Additionally, I am adding a transmission cooler this weekend. Is this a common issue with these cars as the miles creeps up as well as the heat? I noticed that the fans seem to have a high threshold for engagement. Does anyone know of a way to manipulate the temperature setting for these fans to around 190 degrees versus the 215 (guess) or higher setting? The car had the upper failure around 95,000 miles and has a Delphi intake. The car runs pretty fast for a stocker and is a pretty good beater so far.
Any information is appreciated!!
Any information is appreciated!!
07-27-2005, 02:43 PM
#2
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The transmission cooler should help. On 92-95 additional transmission coolers were stock. Most on the forum feel the 92-95 transmissions lasted longer because of the coolers. With that said many have 96+ with high mileage and no problems. Sounds like you are headed in the right direction.
As for the fan thresholds. Yes, low speed fans come on at 215 and high speed at 225. Willwren modified his 93 to put in an override switch. His process and findings below are very helpful and informative. Follow the directions for the 96 if you want to do this.
As well I think Intense sells a kit to alter your fan thresholds to whatever temp you set with a thermocouple
This summer is causing many heat related issues. We feel your pain.
http://www.bonnevilleclub.com/forum/...t=fan+override
As for the fan thresholds. Yes, low speed fans come on at 215 and high speed at 225. Willwren modified his 93 to put in an override switch. His process and findings below are very helpful and informative. Follow the directions for the 96 if you want to do this.
As well I think Intense sells a kit to alter your fan thresholds to whatever temp you set with a thermocouple
This summer is causing many heat related issues. We feel your pain.
http://www.bonnevilleclub.com/forum/...t=fan+override
07-27-2005, 09:19 PM
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We explain this one a lot...
First, the 1997 Bonneville SE, if it has the L36 AKA the 3800 Series II NA, it will have the 4T60-E.... I have not seen to many heat related failures, just a few...
The 180 T-Stat is a good start... The coolant coming out of the thermostat housing and into the radiator is at least 180F, then is cooled by the radiator.... But what a lot of people do not realize is that the Stock trans cooler is internal to the radiator, and is cooled by the coolant before it returns to the engine... I have seen 4T60-E'* run as hot as 230F, and I have heard of them running between 240-260F at times<--- Not good...
I also changed to a 180F T-Stat a long time ago as I was in Florida... Little warm down here most of the year.... About 2.5 years ago after watching my tranny temps in normal driving reach 230F I decided it was time for a cooler... I bought a RV + 7000 Lbs, Heavy Duty cooler... I ordered the lines for a Bonneville with an Aux cooler, and plumbed it all together... Most of the time the trans now runs between 160F-180F depending on how hot it is, and ther engine runs a tad cooler as well...
Both of my Bonnevilles have HD coolers...
Good Luck
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First, the 1997 Bonneville SE, if it has the L36 AKA the 3800 Series II NA, it will have the 4T60-E.... I have not seen to many heat related failures, just a few...
The 180 T-Stat is a good start... The coolant coming out of the thermostat housing and into the radiator is at least 180F, then is cooled by the radiator.... But what a lot of people do not realize is that the Stock trans cooler is internal to the radiator, and is cooled by the coolant before it returns to the engine... I have seen 4T60-E'* run as hot as 230F, and I have heard of them running between 240-260F at times<--- Not good...
I also changed to a 180F T-Stat a long time ago as I was in Florida... Little warm down here most of the year.... About 2.5 years ago after watching my tranny temps in normal driving reach 230F I decided it was time for a cooler... I bought a RV + 7000 Lbs, Heavy Duty cooler... I ordered the lines for a Bonneville with an Aux cooler, and plumbed it all together... Most of the time the trans now runs between 160F-180F depending on how hot it is, and ther engine runs a tad cooler as well...
Both of my Bonnevilles have HD coolers...
Good Luck
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07-28-2005, 10:15 AM
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Transmission temp
Thanks for the replies. I was looking for programmers or performance chips and pretty much didn't find anything significant. I would love to make the fans come on at a cooler temp without rigging up toggle switches. I thought that GM switched the transmissions in 1997 to the 4T65E which is a modified version (What difference?) of the 4T60E. Has anyone heard of the symptoms that I identified in my first post and is this a possible indicator of an impending overhaul?$ 230 degrees seems like a high temp for a transmission indeed. I failed to specify that I have the SE or the "Weak" unblown 3800 
07-29-2005, 12:20 AM
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Well, I've got a 97 SE. Putting a flowmaster 80 series on it tomorrow actually. I haven't had any problems besides the transmission slipping once around 1,500 miles ago, but I think it was just a piece of dirt that caused it.
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