1999 S80 T6 Overheating problem revisited

[Oly_850]

Idont recall the size, but be very careful, these bolts seem to strip out fairly easily, and at hard enough to get to I the first place. I used a slim 1/4 inch drive with the shortest length Torx bit combo I could find.(253) 582-2408

[regent]

Yes, they like getting stuck in there (steel bolts in aluminum); you can drip some penetrating oil and give it overnight to help break loose but be sure to wipe it off carefully before disassembly - you don't want that penetrant to get into the cooling system.
Use some anti-seize on assembly.

[Riba]

Alright, just came back from the job half way done. First the good stuff: the spark plugs look fine, there is no unusual deposits on them, they appear a schoolbook example of good combustion.

Now the bad part: whoever put the spark plugs in probably didn't use anti-seize compound, but even that wouldn't be a problem if he didn't screw in plug #3 like a madman. After running engine for ~20 minutes, I removed five spark plugs with some effort, but #3 wouldn't give. Finally I used a piece of pipe to get me some leverage and the damn crappy Chinese spark plug socket tool snapped. As an additional bonus, the compression tester thread adapter decided to stay in #4 and I could not get it out without long nose pliers. Tomorrow I will get the pliers and put some Loctite on the thread on the other side which will hopefully keep it in place.

Unfortunately I didn't have anyone to help me out, so I just cranked the engine 6-7 turns which should be more than enough. I would prefer to have someone check the gauge while I am cranking, but it wasn't possible now.

Anyway, here are the results (drum roll...)

Cylinder #1:



Cylinder #2:



Cylinder #4:



If I am not mistaken, these readings are quite poor, bordering with horrible. Over the weekend I will remove the remaining spark plug, warm up the engine and repeat the test after pouring a bit of oil in the chamber and see it the value changes.

To be continued....

[regent]

Here is my one-man compression test workaround:

Since my arms are not telescoping/articulating, I deploy my red-neck remote-start switch (one hand with a jumper at the starter solenoid coil, eyes on the gage, my other hand is busy holding the beer
And I make sure I'm not injecting any fuel (pull the injectors' supply fuse)
Your first readings appear to be indicative of a lawn mower/oil washdown syndrome, no?

[Riba]

Here is my one-man compression test workaround:

Since my arms are not telescoping/articulating, I deploy my red-neck remote-start switch (one hand with a jumper at the starter solenoid coil, eyes on the gage, my other hand is busy holding the beer

Nice trick, I will give it a go.

And I make sure I'm not injecting any fuel (pull the injectors' supply fuse)
Your first readings appear to be indicative of a lawn mower/oil washdown syndrome, no?

Now you made me google it. Feels good to know there are still new things to learn even at this age.

I did pull out the fuse for the fuel pump. I am wondering about these readings, if they were correct I should have felt a loos in power, but from what I can tell the engine pulls very nicely.

[regent]

Even with the pump disabled while cranking, the injectors are still firing and fuel is draining nicely onto the walls of the bores (so long as there is some residual pressure in the rail). That's why I prefer cutting off power to the injectors.
Since your engine feels strong, I was beginning to wonder why you would suspect low compression...

[Riba]

Even with the pump disabled while cranking, the injectors are still firing and fuel is draining nicely onto the walls of the bores (so long as there is some residual pressure in the rail). That's why I prefer cutting off power to the injectors.
Since your engine feels strong, I was beginning to wonder why you would suspect low compression...

See subject - I am trying to figure out if the head gasket is blown. I know the compression test will not be conclusive, but it is fairly easy to do so why not. Also, I may be wrong as I never had a chance to feel how a brand new T6 engine is supposed to work....but this seems decent enough as it is. Actually I don't even care if the compression is low as long as I can resolve the damn overheating issue. I'll replace that temperature sensor these days and we'll see what happens.

[regent]

Understood; let's think positive and hope your gasket is fine