Need advice on possible engine rebuild

*Disclaimer, I have posted this question on Reddit yesterday for advice & tons to people advised me to seek help here as well, so the content is copied over with additional details. Hi all, I acquired my 2000 996 cab tip in 2021, bought it for 17k & had a reputable shop clean it up & did quite a few replacements. After all it is a 20 years old car, I purchased with this understanding in mind. Earlier last month I saw the coolant reservoir looks to be lower than usual and muddy, the same time the oil refill tube has some mayonnaise like substance in it. I knew that is not good at all, but still hope for the best when I towed it to the shop. Just got a call from the shop giving me the bad news, the problem is coming from the engine, and a rebuild is recommended by the shop. From what we know so far is, the shop has eliminate all the possible failure points & they have determined the cause is coming from the engine. We have not taken it out or perform any work on the engine itself yet. The shop owner wants to be sure I'm positive and ready to commit before they rush into anything. This is the first time I faced this issue, and I'm just not sure if it's worth it to go through the whole thing. I do enjoy working on the car, did most of the basic maintenance by myself, so I'm more towards getting it fixed properly. The range I was given is around 25k to 35k, which is a lot more than I was hoping for initially. Hoping someone had gone through before can give me your thoughts or advice. FYI I'm in southern California, orange county. -------Above is from the original post-------- I'll be contacting the shop today to get some more clarity, as I was having a hard time processing this info yesterday, so please bear with me. I think I'll ask the shop the following questions 1. What were the spots have checked & isn't failing? 2. Before doing any major work, is there a way to determine what is failing in the engine? 3. What parts are recommended to purchase to complete is job? 4. Timeline

Could be the oil cooler causing the intermix - least expensive fix. Won't be cheap and very time consuming. Here is a good vid: The Red Porsche 996 Is Almost Complete !!! 996 AOS And Oil Cooler Replacement !!! Next would be a crack in the head causing intermix. Last would be cracked cylinder sleeve. Entry point on your car was $17K. Your numbers of $25 to $35K for a full rebuild will buy you a replacement car. I would sell existing car as a roller - $5K and apply that to the $25K to $35 rebuild and replace the car. Very hard pill to swallow. I fear this day with my own car. In fact this actually detracts from the enjoyment of the vehicle as any rebuild on these cars exceeds the value of the car.

Egh, not good for sure. I would check out CogsCogs, https://www.cogscogs.com/search.asp?keyword=engine in the Atlanta area, or give them a call. I bought a used (39k) motor for mine when it went a few years ago. I paid roughly $12k for mine and swapped all the bits along with it. Depends on your budget, but can be done. Otherwise, rebuild yourself. These are not as complicated as people want to tell you. Obviously, there are tolerances to be concerned about. It is a mechanical device at the end of the day. Now, I pull motor in the driveway in less than a couple hours, fluids drained included. Just my .02. Good 3.6: https://www.cogscogs.com/porsche-911...arts-car-.html Good 3.4: https://www.cogscogs.com/1999-911-ca...parts-car.html

Could be intermix from... 1. Cracked heads from an old waterpump when the blade breaks off and lodges in the head and creates heat. If so, it can be fixed by Hamheads in GA. 2. A cracked AOS. Easy fix with a new (UAOS) and alot of draining/cleaning of your cooling system. 3. Oil cooler failure or seal failure. 4. Cracked cylinder from Hydolock (AOS failure). Requires sleeving which means a rebuild. All can be tested for.

It could be a headgasket failing however, I've not actually seen a gasket fail on an m96. Most likely its a cracked cylinder head, or a failing oil cooler. It could also have a cracked cylinder, however if it were cracked enough to leak coolant into the chamber it would be showing more than intermix. They could replace the cooler and THOROUGHLY flush the system, if it works out you should play the lottery. Otherwise, its probably a cracked head which is rather hard to verify without removing the heads. In some cases you can pressurize the cooling system and check each cylinder with a boroscope; if theyre lucky they'll see coolant on the bank thats cracked.

If a rebuild is required, you can... 1. Get a used M96 engine and swap it into your car and take your chances. 2. Get a factory short block and swap it into your car. 3. Find an indy that has the capability to rebuild an M96 of which they will get the required parts from LN or Hartech/Slakker depending on your preferences. 4. Have FSI/LN or Slakker rebuild your engine depending on your preferences.

You most likely don't need a rebuild, I would say the worse case is a cracked head. Len Hoffman takes care of those. Best of luck.

Option is to sell your motor as a running but affected unit. Buy a used M96, put a new clutch, rear main, IMS, and put it back in. All are budget related, but none are bad recommendations. Let us know what you decide on.

OP - Sorry about your intermix issue. Tough pill but not the bitterest to swallow. Check the many years of posts on intermix from 911uk, RL and Renntech if you haven�t already. PT3 will probably weigh in, as will others. What was the manometer reading? They need to rule out AOS internal failure. Was oil cooler inspected? Has the water pump been pulled and inspected? You definitely want to isolate and eliminate possible simpler causes before they tear into the engine. Historically, .1 heat fissured /cracked head or D-chunk is a candidate. Lots of different ways to attack the problem, but only a couple are gonna be right. Good luck, sir.

Rule of thumb explained in detail by PT3 on many previous posts, on the m96. With the exception of a bad oil cooler 1 out of 10 times. Majority of times its 1 of the below. 1) oil only in coolant reservoir = cracked head more than likely. Many times can be fixed by a head repair only. 2) oil in coolant reservoir & coolant oil milkshake on dipstick/sump/oil fill tube = more than likely a cracked block. Babbit crank bearings get destroyed from coolant. Will require a full rebuild and if its driven long enough with the intermix all coolant hoses/rubber parts will also need to be replaced.. jmo

A lot of Shops , Techs, and other Owners will jump to full engine replacement/ rebuild, anytime there is an internal problem, such as intermix....... But if your engine is less than 50K miles, why do so ?? Sure if your engine is over 150K miles then go ahead and replace/rebuild..... A cracked Bank 1 cylinder head is the Number 1 cause of Intermix....A Brand New Cylinder head is about $3500 ... but Lenn Hoffman can repair it for much less ...( cost has gone up but still a lot less than a new head).. Labor to replace a cylinder head is about 10 hours to R&R engine and about another 10 hours to R&R the head...So 20 hours labor plus a top end gasket set and some cam pads and fluids ... Other less likely causes of Intermix are failed oil cooler...failed water pump( could have caused the cracked head).....failed AOS and cracked cylinders...<<< these should also be checked first for "pass or fail tests" .. So two big questions remain before giving a specific advice on action to take ... 1 What was the condition/health/miles of you engine before ?? 2. Any damage done driving with Intermix ?? ( ie. Is you oil a milkshake also ? ) What I'm saying is I LOVE buying engines with less than 50k Miles that have only a cracked head ( I've bought several for $3k ) and just repairing the head crack and having a perfect running under 50k miles engine for little cash ...

I didn�t see a mileage indicated. I had same issue at 95K and naively went for a full 3.8L rebuild, at $20K, that also fixed a dozen other M96 design issues. In retrospect, I should have just had the cracked head repaired (Hoffman will also re-insert valve seals that won�t fall into the cylinder, design fault #10) and replaced some other things without cracking open the case . So, in your shoes, I would follow previous instructions in order of likelihood after pulling engine�.cracked head, oil cooler, etc. If any of those solve the problem, the �while you�re in there� replacement costs (AOS, water pump, clutch, etc.) will be a lot ($5K?) but a fraction of what a full rebuild would cost. Check out a recent PCA YouTube video with FlatSix.

Quotes source post: 20243310

Hi Porschetech3 ! there are so many people suggested me to check out some of your posts/responses and I've been reading them! My car has a little over 105k mileage, AOS was replaced in 2021, water pump in 2022. I don't recall temperature ever going over the 0, the red light does light up sometimes but it is typically during traffic. I'm actually not sure how the oil in the engine looked like, maybe that is something I can ask. The shop owner also states he has tested and eliminated other point of failure at this point. Another info to note, I do recall the owner mentioned all cylinders seem to be just fine, I can also check with him the observation on it. Is it safe to assume work to be done on the engine is inevitable at this point?

Quotes source post: 20242754

That is for sure an option I've been considering, I'll keep the number in mind

Quotes source post: 20243034

Thank you so much for you input. A few of the items you mentioned were replaced around 2021/22 so not that long ago. I'm still absorbing all this information on what to ask and consider.

Quotes source post: 20243334

Oops, that's a critical info I should had included, the mileage is around 105k. I'll definitely check out the video and seek out opinion, the options to not have to open the case is intrigging.