Engine Diagnostics - Intermix

[tonythetiger]

OK, So I have intermix in my coolant, the brown coffee sludge in the recovery tank and have started diagnostics.
My mechanic says step one, he is going to test the coolant for exhaust gases using a "combustion leak detector" product. I looked for other threads using this stuff and saw nothing. Basically, you heat the car up and draw air from the recovery tank. If the test fluid changes color, there is exhaust gases present in coolant. Normally, this would diagnose a blown head gasket, but I am pretty sure this isn't the issue.
next I want a compression test and leak-down.
Is there anything else besides a oil cooler failure (heard this is rare), o-ring failure (again, rare) that causes intermix besides the dreaded cracked head? I haven't heard too many happy stories with intermix, so...
150K on a 2000 Boxster S

[BoxsterSteve]

Originally Posted by tonythetiger

OK, So I have intermix in my coolant, the brown coffee sludge in the recovery tank and have started diagnostics.
My mechanic says step one, he is going to test the coolant for exhaust gases using a "combustion leak detector" product. I looked for other threads using this stuff and saw nothing. Basically, you heat the car up and draw air from the recovery tank. If the test fluid changes color, there is exhaust gases present in coolant. Normally, this would diagnose a blown head gasket, but I am pretty sure this isn't the issue.
next I want a compression test and leak-down.
Is there anything else besides a oil cooler failure (heard this is rare), o-ring failure (again, rare) that causes intermix besides the dreaded cracked head? I haven't heard too many happy stories with intermix, so...
150K on a 2000 Boxster S

Sad to say, but it looks like you'll have to pull a head and getting it welded. I also dread this method of failure on my own MY2000 car. From what I've read, it's usually the Bank1 head that cracks in cyl. #2., allowing coolant to enter the oil galleries. Allegedly a fairly easy fix, compared to other issues that can plague these motors.

[thstone]

There are other ways to get intermix but they are all worse than an oil cooler failure, blown head gasket, or cracked head (none of which are necessarily the end of the engine).

The steps that you and your mechanic are planning make perfect sense and should provide a diagnosis with a high degree of certainty.

Good luck, here's to hoping that its the oil cooler!

[JFP in PA]

Originally Posted by tonythetiger

OK, So I have intermix in my coolant, the brown coffee sludge in the recovery tank and have started diagnostics.
My mechanic says step one, he is going to test the coolant for exhaust gases using a "combustion leak detector" product. I looked for other threads using this stuff and saw nothing. Basically, you heat the car up and draw air from the recovery tank. If the test fluid changes color, there is exhaust gases present in coolant. Normally, this would diagnose a blown head gasket, but I am pretty sure this isn't the issue.
next I want a compression test and leak-down.
Is there anything else besides a oil cooler failure (heard this is rare), o-ring failure (again, rare) that causes intermix besides the dreaded cracked head? I haven't heard too many happy stories with intermix, so...
150K on a 2000 Boxster S

Testing the space above the coolant for exhaust gases is a very common and reliable method to help determine the cause of the issue. If no exhaust gases are present, the intermix can be from something like the oil cooler; but if the gases are found, you have a crack somewhere in the combustion chamber area.

[Gelbster]

It is also (I found) quite a simple ,goof proof procedure and of course you can repeat it to confirm and test a known-good vehicle to verify the kit works.
I sense a call to Hoffman Machine may be next ?
This may ease the pain?
https://newsite.hamheads.com/
https://newsite.hamheads.com/2017/01/16/986-996-porsche-cylinderhead-cracks-explained/

[Jamesp]

Pull the plugs and look at each one. If it is a cracked head the clean / wet plug (or rusty if the engine has not been run) is the cylinder of interest. If they are all the same, it's not coming from the cylinder. next stop is the oil cooler. The head gaskets are bullet proof in this engine and an unlikely failure. Cracked heads are not uncommon, but can be welded up and used again.

[Gelbster]

Originally Posted by Jamesp

Pull the plugs and look at each one. If it is a cracked head the clean / wet plug (or rusty if the engine has not been run) is the cylinder of interest. If they are all the same, it's not coming from the cylinder. next stop is the oil cooler. The head gaskets are bullet proof in this engine and an unlikely failure. Cracked heads are not uncommon, but can be welded up and used again.

As the link above indicates it is possible for the pressurized coolant to leak directly into the oil ways. This would leave little evidence on the plugs. 9xx Motors(Jason) a well regarded local engine rebuilder has a good video showing several such cracks.I'll try to find it.Hoffman in the links and narrative in my previous Post also covers this
https://www.youtube.com/watch?v=rtbXu0jji-s
https://www.youtube.com/watch?v=2wQhkvUHkDc
But James addresses the initial difficulty of diagnosis with the engine complete and running. The pressure tests linked are after a convincing diagnosis because removing a cylinder head is a lengthy task.For example .if the head pressure tested good and then you found the intermix was cused by an "O" ring failure on the Heat X ,you would be miffed.So diagnosis is the critical task.The repair is 'easy'

[tonythetiger]

im getting some confusing information back talking to parts guys.

Question is...Are left and right heads interchangeable (think this is a no)
9961041371R is 2000 boxster S 3.2L head
9961041024R is 2003 boxster S 3.2L head

are these interchangeable? Some say yes and some say no...

what about the 99610492100

[Jamesp]

Originally Posted by tonythetiger

im getting some confusing information back talking to parts guys.

Question is...Are left and right heads interchangeable (think this is a no)
9961041371R is 2000 boxster S 3.2L head
9961041024R is 2003 boxster S 3.2L head

are these interchangeable? Some say yes and some say no...

what about the 99610492100

On my 2003 the castings are the same, but they are machined differently. The AOS bolts to a boss on the right head, that interface was not machined on the left head. Though I don't recall all of the details there were other differences as well. Gelbster, thanks for the education with the videos. That's what the forum is all about. I'd still pull the plugs first as it can be a positive indication of the failure point.

[Gelbster]

Originally Posted by Jamesp

. Gelbster, thanks for the education with the videos. That's what the forum is all about. I'd still pull the plugs first as it can be a positive indication of the failure point.

Agreed -Oh yes - do ALL the simple stuff first . R&R of a cylinder head is something to avoid. Preessure testing as JFP mentioned is also an essential before we go for the dramatic procedures.

[JFP in PA]

Customers facing a possible major league issue like a cracked head or cylinder wall often look at us cross eyed when we suggest running exhaust gas and cooling system pressure tests before starting repairs, probably because they see it as "padding the bill". The reality is by running these diagnostics may significantly change what comes next. If the cooling system presssure test says there is a leak, but the exhaust gas test is negative, we would simply drain the cooling system and pull the oil cooler for further testing. But if the exhaust gas test was positive, our first move would be to drop the engine for a further look.

The time and costs involved are obvious, and your really don't want to end up looking like a total muffin with a perfectly sound engine settling on an engine stand with a leaking oil cooler.

[Gelbster]

I am biased but this is one of your best responses JFP.
Worse , you drop the engine ,pull the head(s) find no leaks ,replace them ,refit the engine and the Intermix continues (from the pesky "o" rings) !
Doing all the tedious diagnostic tests first conflicts with natural impetuosity ? I am better at the mechanical tests than the psychology -so will leave the explanation to others.

[tonythetiger]

Originally Posted by Gelbster

I am biased but this is one of your best responses JFP.
Worse , you drop the engine ,pull the head(s) find no leaks ,replace them ,refit the engine and the Intermix continues (from the pesky "o" rings) !
Doing all the tedious diagnostic tests first conflicts with natural impetuosity ? I am better at the mechanical tests than the psychology -so will leave the explanation to others.

has anyone seen o-rings leak and cause intermix? Im not dropping the engine without diagnostic testing, but thought I would ask the quick question anyway....

[Gelbster]

Originally Posted by tonythetiger

has anyone seen o-rings leak and cause intermix? Im not dropping the engine without diagnostic testing, but thought I would ask the quick question anyway....

Yes. And in case you see no leaking oil/coolant on top of the engine- that is not definitive.
The Heat Exchanger may also leak internally.
See JFP's advice on having it tested.

[j.fro]

The good news about a cracked head is that while you are at it, it's not too much more to get the heads ported for a nice little power and efficiency boost. The bad news, though, is that the "while you're at it" list is long and pricey..
Clutch & flywheel
Valve springs
Re-grind valves
Rebuild lifters
Rebuild fuel injectors
Cam pads/ramps
Chain tensioners
AOS

[Gilles]

Originally Posted by j.fro

The good news about a cracked head is that while you are at it, it's not too much more to get the heads ported for a nice little power and efficiency boost. The bad news, though, is that the "while you're at it" list is long and pricey..
Clutch & flywheel
Valve springs
Re-grind valves
Rebuild lifters
Rebuild fuel injectors
Cam pads/ramps
Chain tensioners
AOS

J Fro, I am not aware that you can rebuilt the lifters and the intake ones are pricey (at least the ones for the 987 engines..)

[tonythetiger]

Originally Posted by j.fro

The good news about a cracked head is that while you are at it, it's not too much more to get the heads ported for a nice little power and efficiency boost. The bad news, though, is that the "while you're at it" list is long and pricey..
Clutch & flywheel
Valve springs
Re-grind valves
Rebuild lifters
Rebuild fuel injectors
Cam pads/ramps
Chain tensioners
AOS

IF I have cracked heads and have them repaired, the valve springs and valves are being worked as part of the package.. Cam Pads and chain tensioner guides are consumables (plastic and subject to friction, but also not that expensive) so there are getting replaced as well...and IMS, of course. What else in the valve train would you consider consumable?

[j.fro]

I had all of my lifters done by Mizpah Precision. I think the cost was around $80. Len Hoffman did the heads and recommended this company for the lifters.