When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hello everybody. I just got a brand new radiator to replace my old one on my 1964 Oldsmobile 98. However, my old radiator did not have lines going to the transmission. The transmission has its own little external cooling box. My new one, for the 98, does. Looking at the factory manual, there were lines that went to the transmission for cooling. But my old radiator and current transmission were not equipped with that. I know I have the heavy duty cooling option if that makes a difference. Could I have the heavy duty hydra matic transmission option? Any help appreciated.
is it possible for me to just block off the 2 lines? I’m a 17y/o so I don’t have much e experience wi this stuff. Thank you guys in advance
is it possible for me to just block off the 2 lines?
Yes, you can plug the 2 ports on the radiator for the transmission cooler lines.
If you use threaded plugs, be sure to get ones that match the threads in the radiator, most likely tubing plugs like the one below. Some radiators come with plastic plugs to block those holes, like when there's a manual transmission. Those just push into the holes. Another option is to just leave them alone as they are not being used, but I like to block them to keep debris out.
The transmission cooler lines could be routed, one into the new radiator and the other one out of the new radiator into the existing external cooler and lastly the one out of the external cooler back to the transmission. This would give extra cooling and the ATF flowing through the radiator cooler first would be brought up to operating temp sooner by the warm coolant exchange in the radiator.
Confirm that any hose used to make connections is rated for transmission pressures, don't use old ordinary fuel hose.
Look that transmission over closely for a Jasper rebuild stamp. Installing an external cooler and completely bypassing the radiator tank trans cooler was the only way they'd warranty a transmission. Your car came with steel transmission cooler lines from transmission to the front crossmember, then rubber lines connected those to the lower radiator tank.
Look at the HydraMatic serial number plate on the left side of the transmission case. If the car came with HD transmission the code on the plate will be OBH64-xxxx.
A standard high compression 4bbl 394 in 3800 series Ninety Eight would have an OA code. A 3800 series with L75 Starfire engine would be OB. OB was factory installation on Starfire, Jetstar 1 and Ninety Eight CSC, all of which were packing S code 394s, and optional on Super 88 and Ninety Eight that were ordered with Starfire engines.
To put this car back to factory configuration you'll have to source steel cooler lines. Unless somewhere like Inline Tube has a pattern or is willing to try making them, a parts car is going to be your only source.
To be honest, unless you drive this car in the cold of winter, there is nothing to gain hooking the cooling lines to the radiator.
What about overheating though?? I’ve been having the car at idle for quite a while while flushing the radiator and the transmission is running quite hot. I am not worried about restoring it to factory, just trying to make sure everything works and stays at optimal temp..
Look that transmission over closely for a Jasper rebuild stamp. Installing an external cooler and completely bypassing the radiator tank trans cooler was the only way they'd warranty a transmission. Your car came with steel transmission cooler lines from transmission to the front crossmember, then rubber lines connected those to the lower radiator tank.
Look at the HydraMatic serial number plate on the left side of the transmission case. If the car came with HD transmission the code on the plate will be OBH64-xxxx.
A standard high compression 4bbl 394 in 3800 series Ninety Eight would have an OA code. A 3800 series with L75 Starfire engine would be OB. OB was factory installation on Starfire, Jetstar 1 and Ninety Eight CSC, all of which were packing S code 394s, and optional on Super 88 and Ninety Eight that were ordered with Starfire engines.
To put this car back to factory configuration you'll have to source steel cooler lines. Unless somewhere like Inline Tube has a pattern or is willing to try making them, a parts car is going to be your only source.
thank you for the information!!! You have been such a big help to me so far. I just looked at the serial and mine is an OA code so it is not heavy duty… I’ll try to look for a jasper stamp but the entire transmission is coated in oil (rust protection from 60+ years ago) so it might take a bit.
What about overheating though?? I’ve been having the car at idle for quite a while while flushing the radiator and the transmission is running quite hot. I am not worried about restoring it to factory, just trying to make sure everything works and stays at optimal temp..
If you have a small electric fan, set it in front of the external cooler and aim it to blow across the cooler while the car is stationary. These things depend on airflow to cool the fluid. Where do you have it located? Between the grille and radiator is probably best location but anywhere in an air stream while the car is moving will work.
Starting to wonder if someone replaced the radiator with one for a stick shift car sometime in your Ninety Eight's life. I've always said Oldsmobiles, especially Ninety Eights, didn't get subjected to buggered repair work like Chevrolets, Fords and Pontiacs did, but I've learned anything can happen in 60 years. Also to never underestimate a determined hack mechanic.
Make sure you run the transmission cooler in your new radiator, and the auxiliary cooler in the car. You can get nickel/copper tubing from the parts store and bend new transmission cooler lines. Keeping that Slim Jim Rotohydramatic cool is going to ensure its longevity (they need all the help they can get).
If you have a small electric fan, set it in front of the external cooler and aim it to blow across the cooler while the car is stationary. These things depend on airflow to cool the fluid. Where do you have it located? Between the grille and radiator is probably best location but anywhere in an air stream while the car is moving will work.
Starting to wonder if someone replaced the radiator with one for a stick shift car sometime in your Ninety Eight's life. I've always said Oldsmobiles, especially Ninety Eights, didn't get subjected to buggered repair work like Chevrolets, Fords and Pontiacs did, but I've learned anything can happen in 60 years. Also to never underestimate a determined hack mechanic.
Quick update: so I talked with the previous owner, and apparently once upon a time the car had overheating issues, which I did know about, so they swapped out the radiator for one that did not have transmission cooler lines and instead installed an external transmission cooler in order to increase the cooling capacity for the engine. Turns out it didn’t make a difference because the clutch fan was actually what was bad.
I think I might buy some tubes to run to the new transmission. I don’t know how much I trust that old cooler for keeping my transmission in good health. It seems to shift gears perfectly so I don’t want to risk breaking it due to overheating
does anyone know if it’s possible to install a temperature gauge or reader in a 1964 transmission? I’d like to be able to monitor the heat if possible.
There should be a pressure test port on the transmission that you can use for ATF temperature. I recommend AutoMeter gauges but you can always buy parts store cheapies if you want to bargain shop.
There should be a pressure test port on the transmission that you can use for ATF temperature. I recommend AutoMeter gauges but you can always buy parts store cheapies if you want to bargain shop.
Dont use the line pressure tap for a trans temp sending unit. If you study the hydraulic chart, you will see the pressure tap comes off the manual valve and is a dead end at the pipe plug. There will be zero fluid flow, and worthless temp readings. Basically you wil be reading the temp of the case, not the fluid.
The best place to put a temp sender is in the pan. That will give you an average temp. If you put it in the outlet cooler line, that will be the hottest fluid because it’s coming directly from the converter.
Dont use the line pressure tap for a trans temp sending unit. If you study the hydraulic chart, you will see the pressure tap comes off the manual valve and is a dead end at the pipe plug. There will be zero fluid flow, and worthless temp readings. Basically you wil be reading the temp of the case, not the fluid.
just sending out a quick SOS, does anyone know what type of transmission filter it takes? I’m going to start work on the transmission soon but I can’t find a part number or anything in the factory manuals about which filter/gasket it takes. I think it’s the slim Jim but I’m not too sure honestly. Anyone have any ideas? Thank you it’s original OA transmission 1964
Scroll down till you find "1961-1964 Roto 10". Select that and it will open a downloadable PDF of internal parts. Never mind the picture of the 57 Chevy, the pdf is Roto HydraMatic 10 aka SlimJim which is what your car has.
It could be a gamble replacing the filter now. You said that the car drives and shifts normally, correct?
so far yea, but the fluid doesn’t appear dirty so I wasn’t assuming there’s metal shards in it or viscosity changes that would occur with a filter change. Why do you say it’s a gamble?
