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Discussion Starter #1
Are there any other reason for milky oil other than a blown head gasket?

Two days ago, cranked it up and ran back into the house to get something. When I came back out there was a cloud of sweet smelling exhaust. Shut is down and drove my other car. Did not think to check and see if it overheated while idling.

Went out today to trouble shoot. Cranked the car and there was a constant squeak (like a mouse being trapped). Sounds a lot like a bad belt.

Drove the car until it was up to temp. Getting an intermittent rotten egg smell (Cat was replaced 60K). The car smells like a hot engine but nothing burning and the sweet smell is gone. Slight and constant knock in the engine but no other symptoms. No skipping, no stuttering, no CEL.

Checked the oil dipstick. Oil there looks normal but seems a little higher than the last time I checked it. Went to replace the oil cap and it is milky white.

Less than 200 miles ago I had a radiator flush. Since then the car has been running hotter than normal but has never run hot. The new "normal" temp seems to be just under the 100 line. You can still see a little bit of background behind the indicator before the 100C line. Never really paid attention before but seem to recall that the indicator used to sit a little higher than half way between the 80 and 100 line.

Is it possible that the temp gauge is not working properly and that car has been overheating?

Only other thing I can think to mention is that I put the Techron in 2 tanks ago. Was going to replace the oil in the next week or so.

Anyone else replaced the head gasket on a SLK 320? If so, do you have instructions? Is that detail covered in the shop manual or would there be some other manual that would have that information.
 

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Sadly Woolly has passed away
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You can get a kit like THIS to check for hydrocarbons in the coolant - usually a sure sign of a head gasket failure. It would also be worth doing a compression test, to check the cylinder pressures are roughly equal across all six cylinders.
 

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how many cylinders ?? its a 320 . don't know what techtron is but if its an oil flush you shouldn't have left it in that long .the milky deposits on your oil cap could be just condensation if your only doing short journeys
 

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Beerbelly-Yes, 320 V6. Due to battery problem this past weekend, I have taken 4 very short trips (less than 10 miles) or just let it idle. The reason I noticed the oil cap is because I just replaced it. Went out to check again and there is water vapor on the new oil cap. The engine has not been cranked since I replaced the oil cap but the engine was a temp when I changed it.
 

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Discussion Starter #5
DH was also wondering if it was a coolant leak in the oil, why would it just show up on the cap but not be visible on the dip stick. I am guessing if it is condensation from the short trips, that would explain it?
 

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You would have to do a lot of short trips to get a noticeable build up of 'meringue' on the filler cap. You can also get it sometimes if the thermostat fails in the 'open' position, so the engine never gets properly hot, but you said in your first post it was getting to normal operating temperature.
 

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Build-up would not be how I would describe it. After beerbelly mentioned the condition, I went and looked it up online. This looks nothing like that. I have posted the photos. Oil filler neck is still black as pitch.

Funny how you describe things online vastly changes the search results. When I first looked it up, I put in milky oil. Got Head Gasket. Looked up milky oil cap and found the condensation issue.
 

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In addition to doing a compression test, you might also want to pressurize the cooling system. There are pumps available for this and most decent garages will have one. They are used to detect small leaks in the cooling system usually by doing a leak-down test. (Watching the pressure drop, if any, over several minutes.) Cheap and easy to do. Easier than a compression test.:biglaugh: Just another tool at your disposal for diagnosis.
 

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There's only one way to get coolant in the oil and that's through the head gaskets. There's no coolant flow through the intake. The first thing I would check is the condition of the spark plugs. Pull one plug from each cylinder and see if it's wet.
I don't think you can use the block test method due to not having a port in the radiator, just the coolant tank.
When I purchased my 320 it actually had both head gaskets blown and I didn't catch it. It gave up after 125 miles of ownership when I replaced the expansion tank cap and it built pressure.
I replaced my gaskets myself by using the Crossfire manual that I downloaded from the forum. You'll need the fixtures that hold the cams in place and a special triple square bit for the head bolts. It actually wasn't that bad of a repair after I got over the initial anger at the previous owner.
My cars runs great now and actually has a little more compression due to having the heads shaved .010".
Contact me if it turns out to be the gaskets and I'll help you all I can.
Randy
 

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Discussion Starter #10
Randy, Awesome, thanks for the offer to help. There are not as many of us with 320 (compared to the 230s) that post DIYs or are available to help. The 230 guys really know there stuff and have been a great help but somethings with the 320 engine are just different so I am really glad to have you around as a resource. Even if it is not the gasket now, it will leak or go bad at some point.

Looks like Beerbelly hit it on the head. Drove the car for 200 miles today and opened the cap and the oil looks like oil. No milky residue on the cap at all. I need to change the oil this weekend to get rid of the Techron concentrate and will let you guys know if I find any other signs of mixing antifreeze.

Going to pull the spark plugs this weekend as well. C4 was wet when I changed them about a 1000 miles ago and want to see how they are doing after the tune up.

There is a burning smell that I have not been able to pin point yet and having electrical issues, I am thinking of changing my girl's name from Molly to Cybil. Every time I crank her up lately it is something new...oh well, at least she keeps me busy.

Thanks again for all the feedback.

As an FYI, have a local shop that will run the compression test for me for about $50 if it comes to that. They have already said they could not fix the issue but they can help diagnose it. They are the same shop that did the coolant flush.
 
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