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Discussion summary
YOUR RESEARCHSudden oil leak on 2003 C4S?
Leading reported evidence
Replace stock imsb
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Performed · outcome unconfirmed · Original poster
The stock IMSB was replaced with an LN ceramic bearing around 11 years ago (and 40K miles ago) when clutch and RMS were replaced as well.
Leading evidence: 'Replace stock imsb' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Check hoses while in there' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
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Performed · outcome unconfirmed · Original poster
Just replaced the water pump on my equally old, but twice the miles 2003 Tahoe.
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Performed · outcome unconfirmed
When the IMS bearing was replaced, you can check at LN Eng with your VIN to make sure it is in their database and you may want to call and ask their thoughts.
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Suggestion
Have your mechanic check the hoses while in there.
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Suggestion · Original poster
six hours for the work, including flushing/replacing coolant.
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Performed · outcome unconfirmed
When the IMS bearing was replaced, you can check at LN Eng with your VIN to make sure it is in their database and you may want to call and ask their thoughts.
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Suggestion
Yep, if you don't have the DIY skills then you do everything you can using the "while you are in there" approach with your indy to help keep labor costs down.
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17 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
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Have had it for four years and not a drop of oil on garage floor. Took it out today. Came back out hour or so later and large puddle of clear oil underneath engine. Steady drip coming from above nut pictured.
Rushed it over to my local mechanic before lost too much oil. Pressure gauge showed normal while driving and no unusual sounds. Doomed?
You sure that's oil and not coolant? I think I see green coolant right where the arrow is pointing and that's where your water pump is and leaks when it goes bad.
I would expect from motor oil. Just replaced the water pump on my equally old, but twice the miles 2003 Tahoe. Assume this will cost me a little more than that.
Idaho911 is right. That is your water pump. Replace with composite, not metal impeller. Consider a low temp thermostat as well. The antifreeze will feel greasy on your fingers, especially if it has a surfactant in it. Have your mechanic check the hoses while in there.
It is a service item. Look at it this way: you are not likely to replace this again. LN Engineering has a nice water pump bundle.
Water Pump Kits for Porsche Boxster, Cayman, and 911 Models (lnengineering.com)
I used this and then one of the hoses failed and I wish I had done that at the same time.
A vacuum lift filler is a godsend when doing this task, you'll need 2 jusgs of the Porsche coolant concentrate and 2 jugs of distilled water.
You might be surprised, a Tahoe water pump can be expensive!
(I have a ls in my Jeep.... the water pump and misc stuff adds up.. )
It must be water pump failure season.
Mine failed on my 01 with 75k miles- turns out it was not even the original pump. This reinforces the notion that the water pump should be replaced every 5-6 years.
Then one of my customer's had his fail at 72k on his 99. Luckily he caught his like you did before the bearing failed completed and sent plastic impeller bits through the heads cracking them in the process.
IMSB failure followed by cam chain wear pad season is right around the corner and before you know it again it will be AOS replacement time again!
--Aaron
The stock IMSB was replaced with an LN ceramic bearing around 11 years ago (and 40K miles ago) when clutch and RMS were replaced as well. Am I at risk? I don't track the car and fairly conservative driver.
GC996 is right. The IMS Retrofit from 11 years ago past its warranty possibly 7 and certainly 5 years ago, so you are at risk. Being a conservative driver is also a risk, so, yeah, you have been living on a prayer. When the IMS bearing was replaced, you can check at LN Eng with your VIN to make sure it is in their database and you may want to call and ask their thoughts. It's possible they would be very interested to see the 11 year old bearing that is still out there spinning.
One thing that may aggravate the water pump issue is lack of use, the seals in water pumps don't like sitting.
If you parking your car over the winter. Before you start in the spring, turn it over a 1/2 turn or so slowly by
hand to get the stiction in the seals gently released. One side benefit of some of the coolant treatments is
their higher level of seal lubricants. (Watter Wetter/ Blue Ice / etc)
The rubber seals sitting there for a extended period of time are tight around the seal surface which
gradually expels all lubrication from between the seal and its mating surface till its basically
adhered to the sealing surface, sudden start cold and it roughs up the seal and then it leaks.
Found this is an issue on tractors and farm equipment since I was a kid. After winter before planting we learned to hand turn
the motor a bit, start it and dont touch ANY of the hydro controls for at least ten minutes,
otherwise every cylinder and seal on the tractor hydraulics would leak. At least on our small tractors a waterpump seal was replaceable.. LOL
Thanks for additional background on IMS Retrofit...My local mechanic diagnosed it as dead water pump. six hours for the work, including flushing/replacing coolant. Way more $$ than the Tahoe. Joys of Porsche 996 ownership.
Wow 6 hours, I had the stepson change the water pump and thermostat, drain the whole coolant system on his gen II C2 in 3.5 hrs. the kid had no mechanical experience, I provided the verbal guidance and the correct tools only. and it was on the lift. I don't see 6 hours.
Yep, if you don't have the DIY skills then you do everything you can using the "while you are in there" approach with your indy to help keep labor costs down. Bigger ticket costs up front but less in labor over time. Never do just one service item if you can do 2 for nearly the same labor cost as 1.
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