# Do these transmission oil cooling lines need replacing? **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [May 24, 2023, 5:25pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791 "2023-05-24T17:25:30Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 24, 2023, 5:25pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/1 "2023-05-24T17:25:30Z")
Vehicle is a 2000 Toyota Corolla LE I looked under my car today and notice that the oil cooling lines need replacing. It seems like the first layer of one of the lines is rusted (3rd pic). The wetness you see is just some crc rust inhibitor for the meantime. My questions are: 1. how crucial is this repair right now? Can I wait 1 more month? 2. The inlet and outlet right angle stems (first two pics) look bad too at the base where it connects to the radiator. Is this part of the radiator? Meaning does the radiator need replacing for that? And does it matter that it’s rusted like that at the base (first two pics) ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [May 24, 2023, 5:41pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/2 "2023-05-24T17:41:36Z")
> [@carg618](#): > > Is this part of the radiator? How are we suppose to know that if we don;t know the type of vehicle you’re talking about? Tester ---
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 24, 2023, 5:46pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/4 "2023-05-24T17:46:15Z")
> [@carg618](#): > > Vehicle is a 2000 Corolla Vehicle is a 2000 Corolla ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [May 24, 2023, 5:50pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/5 "2023-05-24T17:50:53Z")
Those fittings look to be part of the radiator assembly. ![image](https://global.discourse-cdn.com/cartalk/original/3X/1/f/1f70a877c71d1d4d804322eb88d0ae5ca31e4dd8.jpeg) Tester ---
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 24, 2023, 6:04pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/6 "2023-05-24T18:04:17Z")
Where it’s rusted, does that affect fluid leaking or is it just cosmetic at this point? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [May 24, 2023, 6:06pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/7 "2023-05-24T18:06:04Z")
There’s transmission fluid on the fittings, which means they’re leaking. Tester ---
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 24, 2023, 6:10pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/8 "2023-05-24T18:10:22Z")
The wetness is CRC rust inhibitor I sprayed on it today. Any leaking from that area would be coolant though ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [May 24, 2023, 6:16pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/9 "2023-05-24T18:16:24Z")
> [@carg618](#): > > Any leaking from that area would be coolant though Those are the transmission fluid cooler hose connections. Transmission fluid runs thru those fittings under pressure. Tester ---
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 24, 2023, 7:38pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/10 "2023-05-24T19:38:51Z")
I didn’t know this. I thought that coolant flows through them. So when I go to replace the lines, will I need to drain the transmission or radiator? ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [May 24, 2023, 7:44pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/11 "2023-05-24T19:44:14Z")
Well let’s see… replacing the cooler lines is a couple hundred bucks. Replacing the transmission if a cooler line lets go would be a couple thousand bucks. Same equation for the radiator. Replacing it- couple hundred bucks. Radiator lets go… engine quickly overheats… you’ll easily be into the repairs for a thousand bucks. Do ya feel lucky today, well do ya? ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [May 24, 2023, 7:50pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/12 "2023-05-24T19:50:49Z")
> [@carg618](#): > > how crucial is this repair right now? Can I wait 1 more month? Unless you are one of 3 people left on Planet Earth without a credit card then you will have to wait. Otherwise just get the parts and fix it or have it done and next month send that amount to your credit card company. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [May 24, 2023, 7:51pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/13 "2023-05-24T19:51:18Z")
When you remove the hoses, the transmission fluid will drain out of the cooler within the radiator. Very little fluid will come out of the transmission because the engine isn’t running, so the pump in the transmission isn’t pumping. Tester ---
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 24, 2023, 10:31pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/14 "2023-05-24T22:31:29Z")
Ok. I will buy the parts today. Do you think that the rust on the bottom of the radiator is serious enough to replace? ---
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 24, 2023, 10:32pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/15 "2023-05-24T22:32:33Z")
So there are separate passageways for the coolant and transmission fluid within the radiator? ---
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 24, 2023, 10:33pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/16 "2023-05-24T22:33:23Z")
I can fix it myself but I don’t have as much time as I’d like. But that’s ok. It will only take a day to repair. Do you think the radiator rust is bad? ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [May 24, 2023, 10:46pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/17 "2023-05-24T22:46:53Z")
There’s a small radiator within the radiator that transmission fluid flows thru to be cooled. ![image](https://global.discourse-cdn.com/cartalk/original/3X/0/9/09b687b29cb6610d3defafdfcdc4fa54324c30f0.jpeg) Tester ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [May 24, 2023, 10:54pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/18 "2023-05-24T22:54:33Z")
I expect all you have to do is replace the rubber hoses. Be sure to purchase the correct hose type and size b/c as mentioned above, the transmission fluid is under a lot of pressure. If you want to worry about something, the main risk is a leak in the transmission cooler inside the radiator. That could allow coolant into the transmission, and quickly ruin the transmission. On a 2000 Corolla, that possibility seems pretty unlikely. No harm done to ask your shop’s opinion of course. They might look at the coolant in the radiator, checking for an oily film, indicating a small transmission cooler leak. They could also pressure test the transmission cooler presumably. In the absence of any visible leaks, doing nothing other than cleaning the areas & monitoring the situation seems like a pretty good option too. ---
**Author:** ![old\_mopar\_guy](https://avatars.discourse-cdn.com/v4/letter/o/6bbea6/32.png) [@old\_mopar\_guy](https://community.cartalk.com/u/old_mopar_guy)\ **Post date:** [May 24, 2023, 11:20pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/19 "2023-05-24T23:20:51Z")
Yes, and frankly, since you didnt know whether transmission fluid or coolant flowed through the lines, you should probably have this done by a pro. And when he suggests replacing all the coolant, and the thermostat and all the transmission fluid, do it. ---
**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\ **Post date:** [May 24, 2023, 11:37pm UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/20 "2023-05-24T23:37:55Z")
> [@carg618](#): > > The wetness is CRC rust inhibitor I sprayed on it today. Unless you intend to replace the rubber hoses anyway, suggest to clean that off of the rubber asap, it might degrade the rubber and cause a leak when you wouldn’t have had one otherwise. ---
**Author:** ![carg618](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@carg618](https://community.cartalk.com/u/carg618)\ **Post date:** [May 25, 2023, 12:12am UTC](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791/21 "2023-05-25T00:12:35Z")
Lol I’ve done plenty of car repairs myself. What does it matter if I thought that coolant flowed through? Does that make the job harder? No. It’s just a different fluid. Doesn’t make any difference to the repair [Next page](https://community.cartalk.com/t/do-these-transmission-oil-cooling-lines-need-replacing/190791.md?page=2)