DIY or shop

I was asked to repair a 996 with oil in the coolant. If it were my car I'd be all over it. I've done 928 and 930 engine rebuilds and pinned coolant pipes on my 996 turbo so I think I got skills. WW Rennlisters do?

I rebuilt mine, not hard. Reading too much makes it appear overwhelming and all doom and gloom. It�s not 😉

I think the first thing to do is find the root cause. It may just be a failed oil cooler. I would pull that first and test. Next would be a cracked head and that can be repaired without spitting the motor. U may also want to scope the bores for scoring. If u r just looking for a decent motor i would just buy a factory short block and have the heads done by Hoffman. If u look at the cost if parts it makes senss because u just cant re-ring these motors. The bores oval and require expensive sleeves and then u need new pistons. If u do decide to rebuild get the Raby video sold by Ln Engineering. U will make less mistakes and i think doing the work yourself if u r mechnically inclined is very doable.

Thanks for the reply. My issue is space and time. I'll be doing it in my driveway. When pinning my 996tt a hydraulic table was all I needed. Pulling heads will require at the very least an engine stand. Then I'm worried about the WYAIT. Timing chain guides, IMS, deteriorated hoses etc. I haven't found a WSM. If the heads need welding then that's another 1-2 months shipping them off. Trust me it's cheaper the ship a whole car rather than an engine. Heads might be the same price. Just thinking I'll be doing a lot work for insufficient compensation. I guess � shop would charge 10k all in. That means I would charge 5k?

If u r doing it for side money then i wouldnt touch it except for putting a short block and heads on it. If u take it apart u r gonna own that repair and there r way too many things to go wrong during a rebuild.....expecially a first time m96 motor. These full rebuilds r $25-30kish and surprising little is labor. Go ahead and price out a Ln-E block, pistons, crank(as most r in bad shape), chains. 4 years ago i was at $17k in parts and that was before pricing went ski high. This is why i suggest a short block over a rebuild. It will save a ton of time and some $. Frankly i think u r jumping the gun and u should check the cooler, head gaskets never fail so if its not the cooler it gonna be a lot of $.

This is the answer I was looking for. It's bubbling and spilling out of the overflow reservoir which would indicate head correct? No smoke on starting so I think the bores are ok. Guess I could start with the oil cooler. If that doesn't work then walk away. Only LN for long blocks?

There r others but they do the best nickasil sleeved case halves. Because if u r gonna do it u should fix the shortcoming from the factory. If u r not gonna do nickasil just buy the factory short block. If i was gonna pay someone i like @Slakker product but u dont think they sell or remanufacture just the case halves. He can correct me if im wrong.

rufrob is in Japan so shipping would be an issue.

I think you need to find out where the intermix is happening, then decide.

In fact there are 2 cars. I'll try one and let the only shop in town do the other.

I did a 996 rebuild two years ago. It had an intermix where white smoke was being blown out the back. It happened to have 2 cracked cylinders. The rebuilt LN Engineering block did the trick. It was totally DIY-able if you have some engine experience, being very careful, and learn all the right lessons,

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Do you want the possible liabilities?

I've run through everything I can think of from just an oil cooler to cracked heads and scored block. So I think I've covered it all. Just need to make sure the owner completely understands I take no responsibility for what I find, get the car start turning the wrenches and report.

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I would not be worried about what you find, but if the motor has a problem after you fix it, or worse yet, fails, after you work on it, then the owner may have a different opinion about the problem and let's not forget there are 1.3 million advertising attorneys in the US. Still, I always try to help when I can.

If the engine is still in the car, you could pressurize the cooling system to at least 25 psi (we pressure test blocks at 40 psi in the shop) and drop the sump and pull the spark plugs to see if you find coolant intrusion into the crankcase and cylinders (should be able to validate if you have cracked cylinder easily that way, assuming you have a bore scope). I've never actually seen one of the heat exchangers fail, but I know there are some documented failures here on rennlist. That's another easy one to rule out. If the water pump is failing or failed previously and there is a new one on the engine, I'd wager it's a cracked head, especially if it is a 2000 996. One poster suggested distance is an issue. We support customers worldwide. Shipping is a non-issue. Regardless of how it's shipped, you have to pack it like it's going to be launched out of a cannon and insure it for full replacement value.

Quotes source post: 19866221

Here�s a way to easily test the heat exchanger: https://www.stomskiracing.com/produc...changer-tester

You Tube https://hamheads.com/2016/12/01/m96-...-general-info/ https://hamheads.com/2017/01/16/986-...cks-explained/ https://hamheads.com/2016/10/20/m96-crack-repair/

Thanks. This project makes me oscillate between can-do and just walk away and enjoy a 951 restoration instead. Leaning towards the 951 now.

Quotes source post: 19861115

I gotta ask, and I realize I'm asking someone probably in the top five of most knowledgeable on Rennlist (or maybe top three): How does a failed oil cooler (heat exchanger) cause intermix? I've had my oil cooler out to test and replace the O-rings. There are no common walls between the oil path and coolant path. Only the fins(?) connect the two paths, right? Without a common wall any corrosion or mechanical failure would only cause oil or coolant to leak outside of the engine. For the O-rings, if they all failed, they will also leak outside of the engine, but there is no path to mixture. Ps: I recall Raby commenting he had only seen intermix caused by the oil cooler once, but no elaboration.

The oil cooler had failed on mine and caused intermix. Pressure test revealed it.

That design is a heat exchanger which means the coolant removes the heat from the oil. For it to work, there has to be a common wall. In the installation position of that "cooler," there is no air flow to speak of so there is no air cooling effect. In fact, there is no fin for air to flow through.

Yea the oil cooler has 2 chambers so oil and water both pass through it. An internal crack will cause intermix. https://theengineeringmindset.com/ho...changers-work/

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Thanks for the link. Not the way I thought they were constructed. Incidentally, even Porsche calls it an "oil cooler". "heat exchanger" is only noted as "other names".

Quotes source post: 19862137

Hartech is another, quality option. Slakker is a partner of theirs. As someone that has done this in my home garage, this is doable.

For sure avoid direct plating the stock block. Seen too many that crack afterwards, especially if bored out, and don't get me started on surface finishes. If you don't own a profilometer and precision measurement equipment, you're pretty much screwed, unless you have someone check it. We have people all the time send us parts to check that were done by someone else :-)

Lock the cams in place, pull the valve cover, and do a leakdown test. The cracked head will reveal itself fairly quickly.