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1993 Transmission oil cooler leak - Major problem

2K views 21 replies 7 participants last post by  Country Dude 
#1 ·
If there ever was a time to get some advice this just may be it.

I just discovered I have a leak in the transmission oil cooler inside the radiator. Yes .. not sure if it is rare but I am told this is a major issue.

The overflow tank on the radiator showed increased volume and it showed a slightly rosy color and frothy looking. I don't look under the hood every day but on my way to a destination the low coolant light came on. I then looked under the hood and saw this fluid in the rad overflow tank. I had to complete my 70 km round trip and then parked the truck.
There is only one place this extra fluid could be coming from and with the rosy color it pretty much indicates transmission fluid in the rad and probably some radiator fluid in the transmission.
The rad is out and drained. I did have a similar radiator with a good transmission cooler; so the 4 core radiator is in a radiator shop getting repaired.
Question: Can the transmission be saved.... it is a 4L80E --- hard to come by around here-- really only on a rebuild basis and expensive at that. Will flushing do the trick --- who is best to do it to ensure all the glycol is removed from all parts of the transmission and torque converter etc... what about longevity of the transmission.... how harmful is the glycol to the transmission...

The transmission dipstick look like almost normal -- but you do see some rosy traces in there ... because the rad overflow has increased in volume it would suggest to me that fluid was sent mostly into the rad rather than into the transmission. I do not know how long this fault has been there. Like everything else it probably started slow and then progressed. I have never heard of this happening -- certainly the first for me.

OK that is my story - hoping to get some feedback - any experiences out there. After this happening my first reaction is to get an external transmission cooler so transmission and motor cooling are totally separate.
A person is second guessing how good the TOC is in the radiator I am taking it from and thinking one may avoid a similar problem down the road.
Thanks.
 
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#2 ·
I did not mention that the truck is a 1993 Chev Silverado 3/4 ton with 6.5L diesel. The original radiator was initially replaced with a 2 core radiator --- work was done by a rad shop which used the old rad housing and put in the 2 core radiator. The transmission oil cooler remained in the original radiator and should still be good. I found the 2 core rad not adequate so obtained a complete 4 core radiator and it is this rad with the TOC problem... hence the logic to rplace the 2 core rad portion with the 4 core in the original rad. Its the trany that is the issue. Hope I did not confuse anyone. thks ---- any thoughts from anyone.
 
#4 ·
You need to drop the pan on the trans and inspect for any wear like metal pieces and abnormal clutch material. If all looks normal then do a complete flush and a filter change. Not a hard job. But if you are not comfortable doing it have a shop you trust do it.
You will also need to flush the cooling system once you get it back together. Oil and coolant don't mix and can cause problems. Especially if you refill with Dexcool.
What I do. For a diesel dump about 3 cups of Cascade dishwashing detergent in the radiator. It is great cooling system flush and will clean all the oil out of the system.
Refill the system with plain water. Idle the truck for 20 minutes or so or take it on a short drive. Then drain. Refill with clean water .Run to operating temp or take it for a spin around the block. Drain. Refill with coolant and distilled water or use the 50/50 mix
 
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#5 ·
Since you don't know how long, it's hard to say what damage is done.

I think since you are driving it, you may be ok, but a full and total drain is in order. Then a very light drive fully up to operating temp for a good week, then another drain and fill... for another week... then drop pan and check for clutch material... If debris is found, your transactions isn't long before all clutches will start slipping.
Rebuild at that point, maybe save drum and steel... torque converter is a possibility also... that lockup will not be immune to the glycol.

good luck.
 
#6 ·
Thanks for all comments. I have dropped the transmission pan and replaced filter before so I could do it again----- it is the rest of the stuff that is still in the trany that is a concern. Someone suggested connecting the discharge of the transmission line at the radiator to a hose and just running until no more fluid comes..... then filling and doing the same thing.....then removing the pan and change filter and filling again.... and that should do it. I have never done this --- it sounds fairly easy but I do not know how effective this is and is there is any danger of running too long that would hurt the transmission. That could be about 40 liters or approx 40 gts of Dex III plus another fill. Cost of Dex III for 18.9 liters is about $82.

Is there a post somewhere as to how a DIY flush is done.

Jiffy lube says they have a gadget that they connect the cooling lines to that will flush the transmission. Cost is about $200. How good is the flush is the question.
 
#7 ·
NO don't do the jiffy lube hey pressure pump fluid and will exacerbate the issue.

Pull the pan, inspect any sediment. Drain and fill then open cooler hose and drain out the fluid until it gurgles and shut down. Fill pan and repeat again.
Then fill up, and bring trans up to temp and set level.
 
#8 · (Edited)
Yup X2 on above. Inspect the pan for issues as I said above. Install new filter ect put pan back on.
Remove lower trans line from radiator.
Stick a hose on it so you can drain it into a bucket.
Start engine and fill bucket with 3-4 quarts of fluid.
Stop engine refill trans to full level. (Helps to have someone helping you to turn the key on and off Maybe you can bribe them with a beer or 2)
Repeat above till fluid comes out looking like new. Expect to run thru around 2 gallons of fluid.
Yes you will burn thru a few gallons of trans fluid but way cheaper than what a shop will charge you. Plus you know you did it right. Rather than some monkey taking shortcuts and screwing up your truck.
Don't buy the high priced fluid to do the flush. Use cheap walmart dex3 fluid. Its good stuff. Its all I use in my transmissions and xfer cases.
Also don't forget flush out the cooling system too.
 
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#9 ·
I never thought of putting dishwasher detergent into a radiator thinking it would foam up so much you may not find the truck for the foam. Have you done it --- if it works on oily dishes why not inside the engine and heater core.... got to get that clean as well... if you have done it and found all is ok I will give it a try once I get my radiator back. Water and detergent is cheap and one can flush it out like this a number of times --- it is summer so no worries about freezing up.

What I am beginning to feel is that I should do the tranny flush myself and learn something in the process. So it is the bottom line of the Transmission oil cooler at the radiator that will spit out the trany fluid into a bucket......and one should be able to hear a gurgle once it is out of fluid.

OK here is the process I will follow:
1. Drop transmission pan ---- look for debris..and other "stuff" -- in the pan and filter.
2. Replace filter/gasket and fill through filler tube.... Wallmart Dexron III is about $60 around here for about 18.9 liters.
3. Connect hose to bottom line at the radiator...start engine and it should pump the fluid out until empty -- should hear it gurgle..
4. Refill through filler tube and run engine again till it empties.... as above. --- I will fill separate containers and inspect what is coming out each time. If there is still some contaminants draining out I will refill and drain again until it looks clean.
5 When clean -- question is should I drop pan again and replace filter and fill ----or should I run it for a while --- few hundred miles/km and then drop pan and replace filter a second time and fill..

Does this seem like a plan??
 
#10 ·
Tommygunner I like your comment:

"Yes you will burn thru a few gallons of trans fluid but way cheaper than what a shop will charge you. Plus you know you did it right. Rather than some monkey taking shortcuts and screwing up your truck."

I try to do most things myself if at all possible. I have only myself to blame if things go wrong I guess but also the hope I will do a more thorough job than someone that has no investment in the item he/she is working on. So far most things have been positive so I will keep on doing it as long as I can.

Thanks for your reply and comments.
 
#11 · (Edited)
Your plan for your trans sounds good. Once the old fluid is flushed out just leave the new fluid in. Then after a few hundred miles. drain and inspect. If the pan is clean there is no need to put a new filter in. Good Luck. I think you caught it in time. Some $ invested now will save you many $$$$ later.
I have been using cascade for many years on all of my vehicles. It works great and does not foam.
If your system has a lot of mineral scale and rust. Follow up the cascade flush with a vinegar flush I use 1 quart white vinegar for cars and 2 quarts for diesels mixed with water.
I just did this treatment Monday on a Ford Ranger I bought. The cooling system was badly neglected. It came out nice and clean with no rust. I could not believe all the crud and rust scale I drained out of it.
When you do the engine flush make sure to turn on the heater so the core will get flushed out too
 
#12 ·
Thanks for the confirmation. I will have to wait for my radiator so I can run the engine for longer time.
Just to confirm --- the lower line to the TOC on the rad is the exit for transmission fluid-- correct? and do I just leave the upper line open --- not sure if it sucks or gets pushed from the bottom one...

Cheers-- I appreciate the help
 
#13 ·
Hello once again. I just picked up the radiator and I asked them to take out the bad TOC. Looks like it sort of bulged at the seam and split there. Makes me question what the pressure is from the transmission or did someone mess with this before. When I purchased the used radiator it had the transmission cooler blocked off so I just assumed it was from a standard where a TOC was not required. I did have the radiator checked however so it assured me all was ok and it was for about 2 years.

I wish I know how to add some pictures because for those never having experienced such a failure I took a few pictures of what was in the radiator.

OK so I will be cleaning out the overflow tank and then replace the radiator without connecting the transmission cooler at this time. I did purchase some cascade powder dish washing soap but wow --- 2-3 cups was recommended... seems a bit much but I will try it after I drop the transmission pan, replace the filter and fill. I will keep the transmission dump in a clean container to analyse later. I did purchase 38 liters of DEX III.... hope that will do for the total flush and fill. Yup -- Wall Mart brand.
 
#14 ·
Just an update on my dilemma.

After cleaning out the overflow tank the radiator was installed leaving the TOC lines disconnected. The radiator was filled with rainwater (as close to distilled water that we have) with about three cups of dishwasher Cascade.

I dropped the transmission pan and replaced the filter. The bottom of the pan had a few fine granules but who knows how long its been there. This is the first transmission filter change this truck has had since I owned it -- purchased with about 118,000 km and it has about 210,000km now. The magnet in the pan is not all metal but some plastic -- it was the plastic that was deteriorating and the deteriorated material was black... soft black material. I scrubbed it all clean and dropped it back in the pan. There was nothing alarming in there ...the fluid was a rose colour not like the bright red of Dex III. After placing new filter the pan was replaced. The pan was filled and then a tube was connected to one of the TOC lines ------ for the Silverado 1993 6.5L diesel it is the TOP line that is the discharge. Approx 4-5 liters were pumped out at a time before the pan was pumped empty and truck engine shut down. I did five such pump outs and left the sixth fill for the extended trial run before I drop pan again and inspect and replace the filter again. The truck shifts quick and responds quickly so I hope it will be ok. In all I have flushed about 30 liters. I took a sample of the final few drops out of the hose to compare when I drop the pan in a week or so.

The radiator and flushing that beast. After bringing to truck of in temperature I drained the radiator. I was surprised how much glycol was in the system and also how much of the rose coloured stuff was still in there .... the original dump I would say there was a 2" layer of rose emulsion -- this time about 3\8 of an inch--- it was the strength of the glycol that surprised me. When the radiator is drained it takes about 12 liters to fill it....which makes me wonder how much is occupied by the motor and heater. I was looking for a motor drain but I could not find it ... I know there is one there but did not see it crawling around under the truck.... would be nice to have a hoist .... no such luck .... even a concrete floor.... just sand here --- so it makes it bad. Placed plastic on the sand so if I drop something it is not full of sand.

Anyway, that is the status. I have flushed the radiator a third time -- each time using 3 cups of Cascade and bringing truck up to temperature using the heater etc. The last fill will be in the radiator until I drop the transmission pan again.

Question: can one leave the Cascade water in the radiator that long or should I drain and just put in water for the longer period of time. Any comments. When I flushed the radiator I did not see rust etc .... not at all.. no crud of any kind... I inspected the bottom of the tray... mind you a lot is not caught because when you disconnect the hose the fluid goes all over the place.

Thanks for your thoughts.
 
#15 ·
One more question came to mind.

What do you guys do for engine clean up. Yes .. I did spill some ATF on the engine and it has dripped lower etc. It will probably burn off on the engine but what about cables and hoses. I do have a pressure washer but don't know what is best clean up detergent to use and how to apply. I believe the pressure washer has a hose for detergent. I have never used it --- but this would a good time to try it.

thanks
 
#16 ·
The block drains are under the motor mounts , so they are very difficult to access with the engine in the truck.
 
#17 ·
Thanks bk95std. I remember replacing a head on a GMC 1993 6.5l about ten years ago and when I started unbolting the head I found glycol coming out so I started looking for the engine block drain..... I did find it at that time with the engine still in .... can't even remember how difficult it was to get at. I was working in a better shop with better lighting and facilities.

Does anyone know the volume of the 6.5L engine block. Never let it worry me before, but , when doing a 50/50 mix of antifreeze should a person look at total volume rather than just the radiator. I will have drained the radiator three times before I plan to fill with antifreeze mix...so what is remaining in the block will be pretty much water. Does anyone compensate for the volume in the block when placing antifreeze?

I do live in an area where we can see -40C/F ---- so it is important for me.

Thanks
 
#18 ·
Total cooling capacity should be close to 27.5 quarts (26L).
 
#19 ·
That is interesting because I filled the radiator a few times and it is about 12 liters. In reality then to get the 50/50 mix one should really put in 12 liters or so of concentrated antifreeze. Mind you most drains and fill do not go to the extent that I have been doing here so there will still be antifreeze mix in the engine block. One should check the antifreeze anyway after draining the rad and refilling.

Well, this kid will run the 1993 Silverado with only 218,000km and drain the rad once more and refill with water only. I will have to purchase antifreeze and do my final replacement sometime next week.

Any other thoughts are still appreciated for sure --- so far all seems to be good --- and hoping I caught this problem in time.
 
#20 ·
Help.. my trany does not want to shift into overdrive when warm/hot. First an update:

1. Drained rad for last time and filled with 3 jugs of antifreeze. Test good to -18C -- not good enough for our area. Need to add more.

2. Transmission -- found on a drive that tranny slipped out of overdrive. Engine rev'd up and did not want to go into OD. I took pan off - replaced filter -- and filled-- took truck for ride... all was well until it got warm. Because shifting is good in all gears and even overdrive I do not think it is a mechanical issue. I think it is something electronic.... solenoids, temp sensing, speed sensing, connector issues, ground issues etc. and the list goes on.

Can anyone guide me through the most likely tests that need to be done to eliminate some things and maybe identify the culprit.

Anyone PLEASE....
 
#21 ·
The connector into the tranny goes porrus causing mixed signals to TCM (trans control module) the valve body bolts get loose and cause all sorts of problems. There is a kit for the former and simply re-torque the bolts on the valve body. you need to pull the codes to check the tranny sensors and check the wiring from them to the TCM there is a tranny section here a member called general bilistien? offers excellent advice. Have not seen or checked it myself for a couple of years. good luck!
 
#22 ·
Thanks for the input ..... I am beginning to read more on this site. As normal, and probably like most we don't come to the site until we have a problem. There is just so much material and also so many things that could go wrong with glycol in the transmission fluid... I guess I need some focus as to what key things to check to get to my specific transmission problem. The general comment seems to be --"get a rebuild" --because the issues may not end.

I will go to a transmission shop to see if they can pull the codes. That is the first thing. Then I will test the transmission electrical plug---key items seems temp sensor since the transmission comes out of OD when warm/hot.

Any other suggestions.
 
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