1983 911 Engine diagnosis help

[WJL911]

Bought this 1983 911 2 years ago and have not had much time to work on it until recently.

Thank you Luccia for share the link to Tec questions and articles.

Read the one "How do you know when it's time for and overhaul".

This is where I have learned alot. Didn't realize I would burn a quart per 1000 miles. I now understand that most of these engines will smoke when they first start.

So back to oil consumption... (oil lose)
The last 2 days I have wash the engine down and to my pleasant surprise , all the oil leaks were fixable without a tear-down. After 1+ hours down the interstate at 80 .... there are NO oil drips on the floor tonight!!!!!

Need help on the next 2 problems and the may be related ....maybe not so I will keep them separate.

#1) compression test:
I pulled all the plugs today for a compression test. All 6 plugs looked very clean and normal.
5 cylinders tested between 145 and 147.
the 6th one (checked twice) was at 75 an 77..... (again this plug was very clean when pulled) I suspect that it may be a exhaust valve...maybe? I have never "stake a valve" but would this be an option? what should I look at next?

2) Did a (starter fluid) vacuum check today and did not find anything. However this engine somedays will run great and idle fine an the next day I can't keep it running. It will lope at idle from 400 to 1500 and then just die. doesn't matter whether the engine is hot or cold..... PITA when your in a city with stop and go lights and having to start it every time you hit a red light...

ideas pleas.


By the way thanks everyone here ... a good place to learn.
p.s. no I don't want a race car OR MODS FOR THIS 911, i WOULD LIKE TO GET THIS ONE RUNNING SMOOTH AN ORIGINAL.

Thanks again

Willie

[Luccia at Pelican Parts]

Happy to help with those links, Willie.

BUMP! Any Pelicans have some input for our community member?

[WJL911]

In the quest to stop all the oil leaks fist..... I found my vacuum leak as well. It was the gasket on the oil sensor on the side of the oil reserv. Little bit like running around with the cap off the oil reserv. Spit sputter hickup etc. .... new gasket... runs smooth.

Next the low compression cylinder..... ordered valve cover gaskets and will re-set all the valve clearances..... I bet they have not been done since new.

New fuel injectors .... 108,000 miles never touched.

If my low cylinder is still low , I plan on doing the "Rope Trick" I've done this on several aircraft engines with success .

stay tuned.....

[WJL911]

Don't know if you guys know Kenny 911 but he is funny to watch on U tube and has some innovated ways to looking for problems. The cigar an plastic tube works, BUT if your a non smoker like me careful not to inhail.... Here I was looking at all the obvious.. hose connection,intakes etc etc. wasn't that at all.

This may sound a bit goofy but the vacuum leak was the gasket on the oil sensor plate that is on the side of the oil reserv. I suppose it's a bit like running around with the oil cap off.
The second issue was this SC does not like it if the oil level is much over the first mark on the stick. If I fill it to the full mark, the oil likes to get sucked up in the fuel plate and that was making it run ruff an smoke as well as well.

So lesson learned for me anyway, check all the small things first. This engine is alot like my Lycoming and continental aircraft engines so on to the cylinder issue.... cross my fingers.
First off I think I'm going to check the valve lash on all of them as I guess this engine need to be check an adjusted from time to time. My guess it has never been done. 2) I do have a compression leak down device if I can get it to work on a auto motor. This engine sat for some time so I'm hoping it may have some carbon build up on one of the valve. I bought some Barryman B12 fuel additive. LAst resort before dropping the motor will be the "Rope Trip" . Google "Aircraft Rope Trick" and that will explain it better than I can.
More later

[boyt911sc]

Willie,

Have a leak down test done on the cylinders. You could inspect the valve's movement without an engine tear down. Maybe just maybe that the cylinder with a low compression number has the valve/s not sitting square or straight on the valve seat. You would need a P7E and P7I Porsche tools. PM me if you need to borrow these tools.

Tony

[WJL911]

Thanks Tony the offer, I'll let you know.

[WJL911]

Good day today.
after 3 tanks of gas with various fuel additives and some MMO, I staked the exhaust valve on #4 and it went from 78 to 150 on compression test. Also did a leak down which also showed good results.
Happy Camper all 6 are 145 to 150 PSI.

So 2nd week of working hard on the 911 , I have basically fixed all but 1 small oil leak and all cylinder are up and running.

On to checking the injectors, then SSI's with CAT bypass

W.

[Brian911T]

Willie,
Glad the car is running better. Could you explain how to "stake a valve". Trying to help a buddy with his car and he has an exhaust valve leaking a little air per leak down test. I have tried searching for this but unsure how its done.

Thanks