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Small leak noticed on driveway coming from bottom of rad, need help identifying
I had a leak that started a few days ago and while it’s not bad, it’s progressively worse.
located the source or what seems to be the source. Wondering if anyone can identify these two hoses or if anyone had to replace them before. I’ve not dug in deeper and the photo attached is one I took from online.
this happened as I was leaving to go out of town, so I didn’t get to investigate. The second photo is actually a photo of mine looking down from the top.
Looks like the rubber of transmission cooler lines are starting to soften.
You may want to take the opportunity to replace your $200 radiator while replacing hoses. Hose leaking is not a bad warning... I have seen aluminum lines in F150 brake off clean... dry tranny ✌️
The rad internal heat exchanger can kill transmission with mayo mix. The only chance we get to fix this is before .... afterwards tranny/car is RIP.
(Honda uses a proven-grade external heat exchanger: when radiator goes, tranny stays).
Last edited by CaliBenzDriver; Nov 7, 2023 at 12:00 AM.
Looks like the rubber of transmission cooler lines are starting to soften.
You may want to take the opportunity to replace your $200 radiator while replacing hoses. Hose leaking is not a bad warning... I have seen aluminum lines in F150 brake off clean... dry tranny ✌️
The rad internal heat exchanger can kill transmission with mayo mix. The only chance we get to fix this is before .... afterwards tranny/car is RIP.
(Honda uses a proven-grade external heat exchanger: when radiator goes, tranny stays).
yes that’s what I was thinking it was the trans cooler lines. The first photo isn’t mine. I used that because it was showing the hoses quite well. The lines on mine are pretty solid, it looks to be the connection where mine is dripping from.
but I will likely replace the rad and lines at the same time.
S-Prihadi (as well as others), I may have the same problem. Oil leak is increasing, but it will take time for me to check (currently -5F tonight ). I have to remove under-panels to narrow location. I have looked in this area 6 months ago, but leak was minor. Leak seems to be increasing in volume.
Basics:
I have almost the same photo as the first. My engine oil level is within spec, but (due to other circumstances) I have not been able to monitor usage rate closely.
Trans has some 3>4 shift and some 3>2 shift issues, but not consistently bad. many shifts are fine.
I have replaced all four wiring pigtails and two of the timing discs (forgot part name) since they were accessible. Other two were very clean with no visible leak and too difficult to change at the time.
If the transmission lines are my problem, some less-than-smart questions:
1) if I am leaking transmission fluid, is this in anyway connected to engine oil fluid level? (I believe not, but I want to make sure . I know there is no trans dipstick.)
2) Is rear differential fluid connected to Transmission fluid (and by default rear diff to Trans) ?
3) How difficult to replace these two lines? DIY? I thought I read in WIS/EPC that Trans must be lifted. Lifting is beyond my tool chest arsenal. When I looked in this area (during warm summer months), I could not see the attachment points of the lines to the Trans. This made me think that I could not access attachment points. Leak was minor then. What might a US MB Service charge to replace the two lines?
Suggestions appreciated (my reply may take some time...)
TIA
I think if you want detect oil leak, first is to identify is that tranny oil or engine oil.
The tranny oil is the easier one to verify. It is blue color if 722.9 7 speed with A89 option and very thin vicosity. Other tranny fluid color is red, for older tranny version.
Since we know tranny oil only has so few possible leak points and main suspect is the hose to cooler manifold, as seen on post 1 photo, I attached it below :
Clean the dirty oil trace.
Wrap kitchen tissue paper/towel around suspected leaky hose region.
Wrap the kitchen paper towel with clear waterproof plastic, so that no other oil from outside hose can stain the kitchen tissue/towel
Drive for sometime and inspect the oil stain.
Here we want to confirm if indeed the oil stain is from inside the hose, or from somewhere else like engine etc.
============
Your questions , in blue , my reply in red If the transmission lines are my problem, some less-than-smart questions:
1) if I am leaking transmission fluid, is this in anyway connected to engine oil fluid level? (I believe not, but I want to make sure . I know there is no trans dipstick.) NOPE
2) Is rear differential fluid connected to Transmission fluid (and by default rear diff to Trans) ? NOPE. The DIFF does not have radiator ( heat exchanger ) for cooling oil like our tranny fluid. DIFF uses its thick body as cooling fin.
3) How difficult to replace these two lines? DIY? I thought I read in WIS/EPC that Trans must be lifted. I have not done it yet, but for my turbo M276, it is no fun Planning to do it this year though. Mid year most likely.
Here is some photos archive when I tried document the tranny oil hose routing for my engine, but hopefully it may give you some idea where the tranny oil pipes+hose routes are for your car, would be similar.
Starting from the tranny to the oil cooler, via AC compressor side :
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ADD more photos.
The tranny oil cooler manifold , a better view.
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Last edited by S-Prihadi; Jan 17, 2024 at 03:15 AM.
Reason: ADD INFO
Hi S-Prihadi,
quick limited feedback. I already did the 'wrapping napkin' test this past summer. I concluded that leak was not from oil cooler, but from farther back. Conflicting evidence made it unclear whether leak was from rubber trans line farther back or if there was a drip from above within the center of the engine hitting the trans line. Since leak was 'minor' at that time, it was difficult to clean/isolate/locate any leak sources. At the time, I could focus on replacing pigtails (etc.) to mostly eliminate that area of potential problem. Your color description is very helpful, I have to analyze. I am also thinking to send to US oil analysis company while I wait for warmer weather so that I will get a) definite answer to Engine/Trans oil ? and b) is oil contaminated?
At this time of year, I prefer to keep underpanels intact to protect from snow/salt on roads. Thank you very much for the guidance. It will take awhile for me to update.
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). I have to remove under-panels to narrow location. I have looked in this area 6 months ago, but leak was minor. Leak seems to be increasing in volume.
It will take awhile for me to update.
