Badness in the coolant tank

I wanted to run this by the wise sages here... About 2 months ago I was looking at my fluids and noted some dried up pink antifreeze on the coolant reservoir. The cap was an original, and it appeared to have been deteriorating because there was gunk on the top. I replaced it and moved on. Fast forward to about a month ago, some antifreeze was seen around the water pump (a tiny amount, see picture) when the car was up getting the spark plugs. No drop in coolant fluid, no overheat, no noise, no CEL. My mechanic said keep an eye on it, that the pump was probably starting to fail, but could wait a bit. Ive been monitoring it closely with no drops noted under the car and no dip in the fluid level. My problem is, I pulled the cap off the coolant to check the level (because my reservoir is opaque) and noted the same sludge I saw on the original cap. A picture of my coolant is shown. Oil was changed about 1000 miles ago and appeared normal. The car: 1999 996 tiptronic. 211,000 miles! engine rebuilt around 170. No oil leak, runs fantastic. oil pressure gauge acts as it should while driving, temp sits around 190 when warm. The dip stick is clean. So of course I'm worried this is motor oil signifying a blown head gasket but I would have expected something more ominous to happen- especially since in hindsight the original cap that I replaced in late July or August had the same stuff on it. What else could this be? My plan was to flush the coolant and change the water pump speculation appreciated reservoir gunk water pump my baby

* Have you been taking a lot of short drives? could be the cause of the "sludge" under the cap (how does your oil fill cap/tube look like?) * Coolant around WP: likely due to a crack in your reservoir. Have a pressure test done of your cooling system to locate the source/cause. NOTE: WP or tank crapping out while driving is not good

Looks like oil sludge on the coolant cap. Any details of the engine rebuild (cracked heads)? I wonder if it's residual coolant oil intermix from previous engine failure. I think it's a good idea to flush out all the coolant and keep monitoring it.

It was recommended to me to replace the water pump every 3 years. Probably wouldn't be a bad idea on top of what the others have said.

Looks like intermix in a very early stage. I'd drain the coolant and inspect it very closely.

Wow... from the looks of the first image, it appears the coolant coagulated. Looks like jellied cranberry sauce. Is that dexcool or did someone get the bright idea to pour Pepto Bismol into the system?

The water pump is shot unless as kromdom noted the coolant tank is leaking. If the water pump is the source of the leak it will have anti-freeze stain/residue on the water pump housing behind/under the pulley. If you decide to replace the water pump replace the T-stat too. Regardless of what you replace I think a drain, flush with regular water, then a refill with fresh Porsche anti-freeze and distilled water is called for. When you drain the old coolant catch it in a *clean* drain pan with absolutely no oil. Clean the drain pan before hand with a non-residue cleaner. I use cans of aerosol brake cleaner. Let the coolant sit a while. If any oil globules appear on top of the coolant there's an intermix problem. It doesn't look like an intermix problem to me though. It looks like the wrong anti-freeze was used or two incompatible types were used.

Sorry - that's oil in your reservoir.

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You are right. I didn't look hard enough and thought that was the underside of the oil filler tube cap. Obviously -- with both eyes open -- that's the coolant cap. There should be nothing on it but water/anti-freeze.

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Yup. Been down that road a couple times. Once with a BMW (head gasket) and again with a Nissan (cracked block). Good luck.

Thanks for everyone's thoughts. A few updates: -checked the oil cap. looked normal. -the debris on the cap is defintely oil as many have said - i siphoned off the top 12 ounces or so of coolant out of the tank so I could take a better look. It was opaque, but pink. I let it sit for a few hours then assessed it. The smallest tiny film of shine over the top showed some trace oils in it, but nothing else and no sediment (See pics). I am wondering if this small amount of oil predates me. Like I mentioned, I noticed it first about 3 months ago and have driven the car about a thousand miles since then because I thought it was just breakdown of the original coolant overflow reservoir cap. There is a small amount of old oil in that reservoir that I just cannot get to to remove it. The small amount of antifreeze is still present around the water pump edges. No such leak is seen around the reservoir, and I have added no coolant to the basin since I bought the car 6 months ago. When I bought the car the center radiator had a leak found on PPI and that was replaced. My plan, as of now, is to replace the water pump and thermostat, flush the coolant line, and refill with new coolant. Then, pray. thoughts?

COMPRESSION TEST.....to locate the cause/source of the oil in coolant. Above plan (i.e. expenses) will not do so.

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Neither of those tests will likely show anything... That's why this issue fools so many people who are not specifically experienced with the M96. The intermix generally comes from outside the combustion chamber.... Inside the cylinder head oil and coolant capillaries. This case appears to have just started. He is super lucky to get an early onset symptom before collateral damage has occurred. Why does this collect in the bottom of the coolant cap first? Because the cap has a built in pressure balancing device that bleeds some coolant past it at high system pressures. The intermixed oil and coolant is very light and suspends easily, going straight to that cap first before anywhere else. This is a super early diagnosis, kudos to the owner. Now he just has to take this seriously assume the worst and hope for the best while finding the right person to save it.

This obviously raises some questions... Since you mentioned a PPI, should we assume that the reservoir didn't look like this when it was done? If it did (but to a lesser degree), it's possible that there was a failure before your purchase, that was repaired, but the cooling system wasn't totally cleaned out and what you're seeing now is the residual oil that was/is coating the internals of the system. This could be good on one hand (the head or cylinder crack has been repaired) but bad on the other (all the hoses in your cooling system may be damaged and ready to fail due to oil in the system). The other scenario (potentially much worse) is that there's a very fine crack somewhere (head or cylinder wall) that could let loose at any time - seeing as you've been driving it like this for the past three months, this seems less likely to me - but you never know... I wish you luck, and hope it's the lesser of potential disasters

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Good point about this being possibly residual after a prior repair.. Unfortunately thinking like this isn't what saves an engine. Last night I was going through scenarios I've experienced first hand like this... One came to mind where an expansion plug was leaking in one cylinder head that never got any worse for years and always looked just like this coolant cap.. Then all of a sudden the flood waters opened up and filled the engine with almost all the coolant from the cooling system.... That plug finally let go. This is an easy fix IF this is occurring now. That said, what id do is an oil service and. Used oil analysis... The results will come back with percentage of water and percentage of potassium, and glycol. This will tell the real story. Buy the oil from www.rndeuroparts.com and select the free oil analysis at check out. Don't use freakin Blackstone!

"That said, what id do is an oil service and. Used oil analysis... The results will come back with percentage of water and percentage of potassium, and glycol. This will tell the real story. Buy the oil from www.rndeuroparts.com and select the free oil analysis at check out. Don't use freakin Blackstone! " ^Yup^... Better safe than sorry! Stop driving the car/running the engine. Do the oil analysis - once you have proper data, devise a proper repair plan!!

If you do one analysis now and find water/ coolant, then you can put a couple hundred miles on it (watched extremely closely!) and then perform another analysis. If the levels are greater after 200 miles, the issue is getting worse. If they are better after 200 miles, the issue could be linked to residual intermix from a previous repair. I do this all the time.

Thanks for the knowledge as usual, Jake. OP, this free "engine life-saving" advice from an expert is priceless, hopefully you take full advantage of it. Best of luck.

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At the risk of sounding like a fanboy, I'm filing away for future reference anything diagnostic that Jake says he does all the time!

yes all the advice has been great! Jake I will replace the engine oil and send it off as you said. Now for some controversy- I put mobile 1 synthetic 0W40 in. RND does not sell this so what would you recommend? This is a southern california cruiser (no track) that occasionally takes spirited drives through the canyons but mostly is stuck in traffic

ohhhhhh nooooo! You have officially done it now. Turned it into an dreaded oil thread. Can't wait to see what happens next......

RUN AWAY....!

hey im just a simple guy looking for simple solutions that wont make my car explode

RND can/will still do the analysis on the M1 oil, but you're only going to get it for free if you buy 12 qts. of JG DT40 to re-fill ...your second one will be based on the DT40 even though there will still be some M1 contamination in there... Good Luck

I got the DT40 and oil analysis deal- the website is not super intuitive and the JG DT40 doesn't even come up as an oil option once you put in the specs of the car. I eventually scrolled down the main page and found the spot I needed, though. Once the results come back in I will post them. I'm a bit scared with what I might find- ignorance is bliss as they say. At least until your engine blows up

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I'm curious as to what your oil analysis said?

UPDATE: I have driven a couple months monitoring the above issue without a problem... I've monitored the coolant, oil levels, pressure monitors, temp, etc and zero issues. I would say I've put 1000 miles on it. No leaks at all under the car. I left it for about a month without checking. Today, the engine turned over a little longer 2 times in a row when starting it up. After that, it went back to starting up as usual. Anyway, I decided I should check things out and there is definitely oil there now. Still not total sludge- when i transilluminate the reservoir it looks bright pink underneath but now looks sludgy on top. I drove it home (4 miles) without a hitch. No CEL, no loss of power (though of course i didnt test it hard), no puddles under the car. Nothing. PSI reached all the way up as it always does. I had driven with medium aggression through some canyons the morning I noticed the sludge and it performed perfectly! I am going to bring it into a shop now, but wanted to know if anyone can recommend one in the los angeles area (preferably west LA)- I will post on the local side of the forums I want to get this diagnosed correctly so I want to find the right shop. AS FOR THE ANALYSIS- I sent off the oil analysis. It came with a clear bottle, and a plastic blue cylinder to put the oil tube in with the ALS address on it. I wrapped the info slip around the clear bottle and put it in the blue cylinder, taped it up, and brought it to UPS. They put it in another box (wouldnt allow me to mail the cylinder only) and sent it off. 2 months later, I contacted RND because I had not heard anything. I had the UPS confirmation from the delivery to ALS (even with the receiving guy's name on it), but they have yet to find the specimen. They say they received an unmarked oil specimen around that time but still no word. My guess is that they saw the box with the oil tube in it and thought I forgot the info slip because it was inside the blue container. So, I never got that info. If I do, then I will share!

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Not sure how far Torrance is from you but this shop has Jake's stamp of approval : Callas Rennsport, Porsche and BMW Service & Restoration Center

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No first hand experience but they seem to get good reports and in West LA. http://www.lucentmotor.com

Tony is a great guy and he instructs the m96/97 engine rebuild class with Jake. He spent half a day teaching us how to time the 3.4L and 3.6L as part of the class. You can't go wrong with him for sure.

It looks like Jake called this right on the money, and very early on! There is no replacement for, or shortcut to experience