Clogged piston squirters?

[echrisconnor]

I'm frequently jumping to worst-case scenarios and here I go again. My engine runs hot. I've read all the "hot running" posts and have confirmed that all the sytems I can check are in order. I've got a carrera cooler & fan which works. My on-engine thermostat opens. 11 blade fan, proper mixture & timing... the list goes on. And the engine still runs hot.

So what else can it be? I worry that it could be clogged piston squirters or something else that cannot be easily fixed without tearing into the engine (again).

Any advice would be appreciated.

chris

[Joeaksa]

If you are worried about the small passages being clogged in your engine, you might put some Marvel Mystery Oil in the oil tank and see if it will unclog things.

That said, I would look elsewhere first. How about pulling the alternator and checking that there is not debris on top of your cylinders? You are in the mountains and I had this same problem with a '72 911. Pulled my hair out and finally replaced the engine. Here is what I found when I pulled the cooling shroud off:


A mouse had made a nest in the top of the motor and the front left two cylinders had almost no cooling air. You live in the mountains and something could have gotten in and done the same thing during a winter storage period.

Would also check to make sure that your thermostat is opening and allowing oil to the front cooler as well as making sure that the metal oil lines running forward have not been crimped, thus slowing the flow to the cooler.

Hope some of this helps!

JoeA

[echrisconnor]

Thanks Joe. I've checked all these things so far. I had the top off the engine about a year ago. And, I had the alt out just over the summer. No mice or other junk back there. When I had the engine out, I pulled the internal thermostat and boiled it up. It opened just fine. Also, no crimped external cooler lines and they get good and hot when the car is running...

Still hopeful.

[Grady Clay]

Chris,

How about some real diagnosis. Go buy a digital thermometer and some Type K thermocouples. You should be able to do this under $200. Clamp the thermocouple on the engine out pipe. Put the thermocouple next to the pipe, then a piece of plastic (spray can cap works well) and then a screw-type hose clamp. Repeat on the two pipes to the front cooler, the return to the tank, the oil in the tank and the metal part of the lines to the cams. This will give you some actual quantitatve data at minimal cost.

The hottest oil should be coming out of the engine. The coolest returning from the cooler. There should be an intermediate value at the return to the tank and in the tank. The oil going to the cams should be the same temperature as your gauge.

You can also use an infra-red thermometer but the thermocouple is more accurate.

Perhaps someone works in one of the Boulder labs and you can borrow the set-up. I want to instrument Pelican cobaltblau SC this weekend DE at La Junta.

Best,
Grady

[echrisconnor]

Hey Grady -- thank you. A friend of mine has one of those infra red thermos which I can easily borrow. I've used it already to verify that my oil temperatures were what the gauge was reading. I had checked at the crossover oil line from the sump.

What is your proposed plan of diagnosis though? Should I get the car up to temperature and then confirm that the outbound oil to the external oil cooler is hotter than the inbound. That the cam lines are the same temperature as what the gauge reads? Etc.

Then, should I get a reading off each of my heads or header pipes (I'm running boxless headers) and see if any are hotter than the others?

What specifically should I look for?

[Superman]

Piston squirters are probably not your problem. Those things only function above xxxx rpm's (4500 or 5500, or something like that) and they're fairly fool-proof. They simply are holes in the rods that face upwards, allowing oil in the rod journals to squirt upward at times. Hard to imagine them being clogged. At 6000 rpms they are shaken up and down one hundred times per second.

You're on the right track. If the fan is moving air over unobstructed fins, and if the deflector plates are properly located at the bases of the cylinders, and if the external cooler is getting hot oil, and if the main cooler (engine mounted) is not clogged, then your temps should be acceptable.

[Grady Clay]

Chris,

This is sort of like going to the doctor and saying “I don’t feel good.” The first thing out of the Doc’s mouth is “Where does it hurt?”

The answer is Yes, all of the above. You are looking for something out of the ordinary. One thing you are going to want to do is find a similar 911 and compare temperatures under similar conditions.

Are you going to the DE at La Junta this weekend? I’ll have my thermocouple and a portable Rubbermaid Solution.”

Best,
Grady

PS: If you are worried about the piston squirters, carefully inspect the cam oiling holes for any little debris sticking out. It’s messy but you can run the engine with the intake valve covers off to confirm proper flow to the cams.
G

[echrisconnor]

Maybe I'll back off the piston squirters as a real fear. When I had the heads off a while back, the cam squirters were nice and cean. No junk in there. I had blasted the piston squirters from the outside with carb cleaner, but never split the case so I didn't verify if they would flow. As Sup says, they're pretty foolprof. Give 'em oil under pressure and they'll squirt. given how they're fed, I also can't imagine tons of gook getting in there.

I'm not headed to La Junta this weekend, however I was at Pueblo in August which was where these high temps became most apparent. Even off the track though it runs damn hot.

Maybe the next best thing to check is to truly verify the temperature drop across the Carrera cooler. I haven't verified that this thermostat opens fully, only that the outbound and return lines are hot when the car gets up to temperature. The fan clearly makes a difference here since I have a manual switch to turn it on and off. In traffic this is most apparent that the fan is doing its job.

This may not be the best reference, however a friend with a 3.2 in his car will barely be hitting 180 while I'm pushing 210. This is with moderate driving and not on the track mind you. If I keep the revs high like on a canyon run, I'm easily in 240-250 land. On the track I should be pitting in after 15 minutes and will see 260 if I'm not careful.

[RandyF]

Originally posted by Superman
Piston squirters are probably not your problem. Those things only function above xxxx rpm's (4500 or 5500, or something like that) and they're fairly fool-proof. They simply are holes in the rods that face upwards, allowing oil in the rod journals to squirt upward at times. Hard to imagine them being clogged. At 6000 rpms they are shaken up and down one hundred times per second.

You're probably correct about the engine squirters, but they can clog. Mine did, apparently from a piece of plastic that got in with an oil change. I imagine it was from the tear off part of the screw top. Luckily my mechanic knew how to remove the squirters and blow them out.

That's interesting info that they only function at higher RPMs by the way.

[Joeaksa]

Chris,

I would still like to see if you are having good oil flow to the cooler. Do not believe that its the squirters and if the temps change when you turn the fan on you are getting some flow to the cooler but wonder how much. It would also be nice to have another 3.0 liter car next to yours and compare the temps at the various points. With the IR temp probe that should be easy and you can spot a lower or higher temp much easier with to similar cars to compare.

BTW, 260 is about 20 degrees too high unless you are running syn oil. Dino oil is starting to break down at 240-250 (if not lower) and this is not good.

JoeA

[echrisconnor]

Randy -- what were your symptoms when they did clog? I'm curious to hear about how you found the problem.

Joe -- I'll do a check on the cooler and see if I can easily spot a significant drop in temperature. The one problem is that the thermo catridge for the external cooler is frozen to the point that I can't get it off/open. I had the oil lines off the car a while back and the thermostat in a vice trying to get it open. No luck.

[Superman]

I think some of you may be confusing the cam squirters with the piston squirters. I think the problem here is neither of those things.

More than any other potential cause, I am wondering about the engine-mounted cooler. I am wondering if its vanes may be clogged. Air needs to move through that cooler. External coolers are charming and in hot locales they are essential, but your engine's main defense against heat is the cylinder fins and the engine-mounted cooler. Those things alone should be sufficient to cool your engine except in extreme load or ambient air temp conditions.

[Jon Merck]

Chris,
Do a simple test and drop the temp sensor in a small pot of boiling water. Gauge should read 212 F.

I thought I had overheating problems, temps 265-275 range. Checked everything except the simplest thing. Replaced the temp sensor and everything was normal.

Good luck!
Jon

[echrisconnor]

Sup -- The engine cooler is in pretty good shape. Some of the fins were a little folded, but I straightened them out when I had the cooler off, so it should be flowing air nicely. I have an oil leak coming from the cooler right now so It'll come off in the next few weeks. I can then get a peek at how things look back there and further clean it if necessary.

Jon, I've already verified that the temperatures are real and not a function of gauge error.