Transmission cooler

[KongzTT M45]

 

I have a 2007 m45 sport with about 70k miles..

I recently have had a coolant leak at a metal coolant tree on the rear of the driver side head. I ordered the new part.. It was about $60 new from infiniti.

coolant-leak-at-metal-hardline-t-t587866.html


However.. I noticed the coolant leaking out is actually a reddish/brown color.. I started thinking is this coolant mixing with my transmission via the transmission cooler? I haven't looked into the stock setup for our transmission cooler yet.. But I'm pretty sure it uses the radiator.

Do our cars have a history of the transmission cooler failure.. Resulting in coolant mixing with our transmission fluid?

I plan on doing a filter and flush for the transmission just incase.. But some more info on this wouldn't hurt.


I ran across this post on installing a B&M cooler 70268

06-m45-trans-fluid-change-and-cooler-in ... 62570.html

However I notice in his writeup it mentions it comes with lines etc.. But when I looked up the p/n.. I didn't see it mention it coming with lines at all.

Thanks for any help you can lend.

Shawn

[elwesso]

The B/M cooler may come with a length of rubber hose but that's it. You may need to get some additional hose. The 'general grade' stuff will be good enough for this application.

The sure-fire way to confirm if ATF is mixing with the coolant is to check the trans fluid. If it seems milky, then the cooler is the most likely cause. You DEFINITELY don't want to be driving around like that, milky ATF will destroy the AT in no time.

[svard75]

Hey Shawn,

Although our transmission cooler lines flow into the bottom of the radiator the two circuits are completely separated. The transmission cooler is actually a large alloy cylindrically shaped bar attached to the bottom of the radiator where the cooler coolant flows back into the engine. If your coolant was mixing with transmission either would be a milky color not rusty. Rusty/Brownish color could mean a few things. It could be really old coolant, however typically older coolant turns white not brown. You have a leaking head gasket causing the engine oil and coolant to mix together. This is more likely the cause of your brown coolant.
How is your oil consumption between changes? When you are idling after the engine is a NOT does your exhaust smell like burning sugar?

Also if adding an external transmission cooler is in your future add it inline with the existing cooler to provide the additional cooling capabilities. In general there are a few things to consider when adding an external cooler:
1. Do you really need it? Towing and/or constant track may bring those temps higher than the transmission would like so adding an external cooler would be best. If you don't really need it why add one more item to troubleshoot in case you spring a leak.
2. Placement of external cooler in relation to existing cooler. The most efficient place for the external cooler would be at the front. Mounted ahead of the AC condenser and radiator is the coolest location but you'll have to consider mounting options and routing of lines.
3. Any old or original hose you touch replace with brand new.

[KongzTT M45]

Thanks for the replies.

I don't remember ever seeing any oil residue in the coolant... just looked dirty to be honest.. I just kinda jumped the gun and got nervous when I saw the reddish color.

So I guess thats good news that its not a possibility that it can be coolant mixing with transmission fluid .. (my buddies Nissan Pathfinder had a huge issue where it bled into the other system and ruined the transmission). I may just pick up the aftermarket cooler to keep the temps down. Its just my DD/"nicer" car to drive. I have my f150 crew cab for towing and my built 300zx TwinTurbo for "fun stuff"

I believe it may be really old coolant because on areas that it did spray on .. it left a really chalky white/light brown residue.

I sincerely hope not and don't believe it is a head gasket.. I haven't had any issues with overheating or anything.. even when I changed the oil.. the oil looked good.. and the consumption was almost non-existent. I bought the car used with about 70k.. very very clean car.. lets hope that the lady owner kept up with her maintenance like she took care of the aesthetics and interior.

Never noticed the coolant burning smell until this incident.. Funny thing is.. I stopped over a friend's house and smellled the sweet smell.. I thought they were cooking breakfast.. I walk into their house and they were.. so I just attributed that with the food.. Then an hour drive later, I go into store and smell it again and was like "oh s***" and saw the steam. Luckily it never left the proper mark for temperature. I kept stopping off the side of the road to make sure it was topped off.

I ordered the new part.. going to install once it gets here.. Then flush the radiator and the transmission with some NISSAN J-matic fluid. I guess i'll change the pan gasket and filter too for transmission. Might as well do the rear while i'm at it.

Anyone have a how-to on how they flushed their transmissions? I just don't trust bringing my car into someplace even though I don't have the machine.

I guess I could just keep doing the drain and refil method for a few days straight.. just wastes a lot of fluid IMO. I've been a mechanic/fabricator professionally and hobbyist for about 15 years... but the older I get.. the less I want to mess with lol.

thanks again for any help!
Shawn

Hey Shawn,

Although our transmission cooler lines flow into the bottom of the radiator the two circuits are completely separated. The transmission cooler is actually a large alloy cylindrically shaped bar attached to the bottom of the radiator where the cooler coolant flows back into the engine. If your coolant was mixing with transmission either would be a milky color not rusty. Rusty/Brownish color could mean a few things. It could be really old coolant, however typically older coolant turns white not brown. You have a leaking head gasket causing the engine oil and coolant to mix together. This is more likely the cause of your brown coolant.
How is your oil consumption between changes? When you are idling after the engine is a NOT does your exhaust smell like burning sugar?

Also if adding an external transmission cooler is in your future add it inline with the existing cooler to provide the additional cooling capabilities. In general there are a few things to consider when adding an external cooler:
1. Do you really need it? Towing and/or constant track may bring those temps higher than the transmission would like so adding an external cooler would be best. If you don't really need it why add one more item to troubleshoot in case you spring a leak.
2. Placement of external cooler in relation to existing cooler. The most efficient place for the external cooler would be at the front. Mounted ahead of the AC condenser and radiator is the coolest location but you'll have to consider mounting options and routing of lines.
3. Any old or original hose you touch replace with brand new.

[ale2and]

The color can be from water pump impeller blades also. If the blades are steal and someone used hose or sink water instead of distilled water when they added coolant it can cause blades to get surface rust.