83 SC - check operating temps for each cylinder
 

Continuation from this thread: http://forums.pelicanparts.com/porsche-911-technical-forum/1032675-andial-2-9-engine-refresh-budget-16.html#post12014740


Following Tom_in_NH suggestion, I used my HF laser thermometer to check the operating temps for each cylinder in my 83 SC.

I pointed the laser dot at cylinder 4/5/6 exhaust --- actually the intake of heat exchangers, as noted by red dots on the foto. At engine operating temp, dashboard gauge, just above the first mark:

#4: ~ 180 ~ 190 F
#5: ~ 190 ~ 200 F
#6 ~ 500 F !!!!!!! --- why is cyl 6 so much hotter? I measured at least 3 times for 4/5/6 and got similar results

I was not able to reach 1/2/3, so pointed at underside of the head exchanger. Got similar results with 1 & 2 in the high 100's, and #4 much higher 350+.

Does that seem normal, what could be happening w Cyl 6?

CONTEXT: I've revived, and restarted the car, after it sat for 3+ years in my garage. It's been a few weeks now, I've started the car ~ a dozen times, and ran/idled for at least 75 min altogether. It is not running "rough" but could be smoother. Engine shakes more that I'd like to, an it could sound smoother. Changed/new: fuel, fuel filter, fuel pump, spark plugs, distro cap & rotor. Adjusted: timing and idle speed

http://forums.pelicanparts.com/uploa...1685832720.jpg

Did you take these measurements when it was warming? Normally the area that you are aiming at temps are closer to where #6 is, 500 deg F is normal for a warmed car.

You should check the temps, at each cylinder at close intervals as the car is warming up from cold.

Clarification……..
 

Silber,

Are you aware that the cylinders #4-#5-#6 you have indicated with the RED dots are actually for cylinders #1-#2-#3?

Tony

If you do have a big discrepancy, a spark plug read on a properly warm engine should tell you a story.
Lean = hot. Rich = cold(er). You may have an injector or FD tuning issue.
Further investigation would tell you - injector patterns, fuel volumes.
Alan

Tony - yeah, I am aware. 1/2/3 on driver side; 4/5/6 on passenger side. The red dot markers were just to illustrate where I would aim the red dot w the IR thermometer.

When I took the measurements, I could only reach 4/5/6 at the intake of HE's.
For 1/2/3 could not reach same spot.

But, after I shut the engine I looked under the car again. If I go hear the muffler exit pipe I could aim/reach 1/2/3. But I'd have to work quickly to minimize breathing in exhaust fumes directly from the pipe.

What is a "spark plug read"; how do I do that? Do you mean aim the IR thermometer red dot at the spark plug, or the rubber wire/connector?

Injector cleaning and FD tuning/cleaning could be needed. The car sat for 3+ years in my garage.

I'm going to record another video of the engine running, post here, and ask the experts if they hear anything is off.

Reading the plugs - checking the burn and timing issues. There are lots of threads on how to- not just on Pelican. You pull the plugs and inspect them for colour of burn and other tell tale signs.

Checked out mine. Car was fully warmed up after a hot summer drive in Texas then idling on lift:

Cylinder 1 - 440
Cylinder 2 - 382
Cylinder 3 - 375
Cylinder 4 - 372
Cylinder 5 - 370
Cylinder 6 - 372

What are the normal operating temperatures?

Looks like number 1 is lean.

@Alan L - Thanks for clarifying. What story do these fotos of the old plugs tell?? Sorry, not the best quality fotos.

I took these fotos right after pulling old plugs out a few weeks ago. This was after the car sat in the garage for 3+ years. I've owned the car since 2010 and put ~ 6K miles on it. First time plugs have been changed under my ownership. Service records/receipts show last spark plug changed in 2002 @ 143K miles, but there is a gap in service records. At worst, the old plugs in foto are over 20 years old, with 20K miles! You can see these are Bosch when they were still actually "Made in Germany"

I'd would hate to remove the new plugs to assess. It was such a pain getting old ones removed and new ones installed. I'd rather not go through the process again, at least for a while.

http://forums.pelicanparts.com/uploa...1685987971.JPG

http://forums.pelicanparts.com/uploa...1685987971.JPG

http://forums.pelicanparts.com/uploa...1685987971.JPG

http://forums.pelicanparts.com/uploa...1685987971.JPG

Idle vs part/full throttle.

Did a flow test at idle, part, mostly full throttle when engine was out several years ago.
Didn't want to mess too much with the cis at that time. All new injectors.

Idle: one injector had lower output than the rest.
mid/full: roughly the same for all.

I suppose you want the car on the road driving under different conditions, but even then, can you catch full load?
Once you stop, I'd guess even for a minute, all bets are off as to what you're measuring, mostly idle conditions, which may not be too relevant.

Very recently bought:
Thermo couples on the bottom are 10 ft long and good to 600F I believe.
You'd need three of the readers at once and then glue the couples to where you want.
Then drive.



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Looks like the "red dot" is just a laser pointer.

An IR thermal scanner gives a more complete picture.

Great points. But, first things first --- get it sorted out @ idle. It is amazing what equipment is available out there now for consumers, and DIY'ers. For the time being, will just have to live w the IR gun w laser pointer and take temps @ idle.



A full IR scan would be very interesting to see. Too much money for me!

Your doing great.

She deserves the best you can afford !

You have several threads going, so I'm not sure if you have run a "delivery test" yet. That will tell you if your fuel flow is the same to each cylinder. With those variations in exhaust temps, I think you're running too rich in some cylinders, and too lean in others.

@ 83_Silberpfeil - cylinders 3&6 usually run a bit warmer than the others. However, I think you had mentioned that the car recently sat for a period. After my SC sat for a year, in a pristine garage, mice had packed the area under the cooling shroud at cylinders 3&6.........They ran very hot!

“ A full IR scan would be very interesting to see. Too much money for me!”…

When you get all others stuff sorted, you might be able find or contact a neighborhood hvac or home inspector tech nearby that has a FLIR.
Some carry one that’s portable for use a cellphone attachment for iphone/android ($450) to locate cold/hot spots ranging -4° to +700°F.
Might even be able to locate an active rodent infestation !

Appreciate you following my progress and thanks for the compliment here!

Yes, for sure --- >>> 'can afford' <<<

No fuel flow test yet. I'm sure I'll need to do that sooner or later. I would not be surprised if there are issues w proper, even fuel delivery at the moment. Recall that the car sat for 3+ years inside a garage. Once I get it on the road and drive under load, add more fuel and Techron, may be the system will "flush itself out" and get a bit better.

Anything is possible. There are rodents that live/hide in the ivy slope @ front of house. Do rodents have a preference for cylinders 3 & 6? Or may be there's more room in that area?

Nice instrument, thanks for sharing.

I doubt the mice have any preference for a particular cylinder :). It's the cooling fan that's blowing their bedding all the way back to 3 & 6.