UberScheitzer

Hello,
After nearly 4 years of sitting around waiting for my father and I to finish the brake system and replace the battery, we finally got our 1974 Porsche 911 (2.7L) running today!!!

However, when we started the engine, we heard a strange, rough and inconsistent rattling noise coming from the engine compartment. We decided to turn it off after about a minute of trying to think what it might be, and thought we should check the oil level (even though we knew it was previously full on oil, was not burning oil before, and there was no leak). We found that we had to add 3 quarts to get it at the correct level, which is mind boggling as to where the three quarts went. Also, when turning off the engine, we hear a winding down rough noise that does not sound normal. Any ideas as to what the cause might be?

Any assistance is greatly appreciated.

Thank you,
Jason

mo_gearhead

Well, first off you should only check the oil level with the engine at operating temp, idling, on level ground. If you put three more qts. in, you have most likely overfilled it! (NOT GOOD).

It sounds to me like the chain tensioner(s) may be your source of noise. More investigating may be in order.

theiceman

Yeah you just overfilled your oil tank for sure ... you say it's a 2.7 L ? well I would be pulling those valve covers and looking for whats left of a head stud rattling around under the valve covers in case it has pulled out. Also the tensioners for sure, especially if it does not have the updated carrera tensioners . I think taking off the chain covers is in order to check it out.

Good luck. .

Mike Murphy

Prior to starting an engine that has been sitting for a long time (over 1 year), it is wise to pull the spark plugs and shoot some loosening oil into the combustion chambers to prevent ring damage (they are usually stuck to the cylinder walls due to rust. Also, the oil should be changed before starting.

Does the noise sound like chains? If I'm not mistaken, these 2.7s should have the chain tensioners replaced with the newer, updated Carrera-style tensioners.

UberScheitzer

Oil was checked multiple times at operating temp, no overfill. I did that once before on my first oil change.

Motor is a 2.7L and has the upgraded carerra tensioners. I think they were done with the full motor rebuild about 12k miles ago, but will look at them regardless. Will also look for a loose stud.

Thanks,
Jason

theiceman

Good luck and let us know what you find. Personally I would not start that engine again unless you find a root cause.

Graufuchs

Good thing i checked this thread and checked my oil..was 3qts to high....after following PO refill instructions.....ran engine for about 1min with to much oil.....drained and started up fine and no strange noises other than the 1 stupid valve thats outta wack. Thank GOD. BTW what can happen if you over fill and run car for long period of time? Mines a 87 3.2 BTW.

Mike Murphy

In the end, engine damage. Oil will overflow past the rings and get burned along with the gas. This results in pre-detonation, poor gas-mileage, hard starts and carbon buildup.

madmmac

The excess oil can come up through the breather into the airbox and gum up you MAF sensor and the related path/parts in your intake.

Graufuchs

Thx good thing I caught it!!

theiceman

fty you are probably fine ...

the first and biggest sign of overfilling as pointed out is the oil spilling out of the tank breather into your intake and a massive plume of Blue smoke like your engine just exploded. You would look like a Bond car going down the street.
In conventional engines excess oil in the crankcase would be mixed with air as the crank acts like a giant blender and mixes it all up, of course all kinds of air in the oil is very bad.

In Dry sump systems it is all pumped out and the excess is in the tank , leading to said smoke screen. You must be a conserative driver because hard cornering ( usually right handers ) usually causes the oil spillover on overfilled tanks .
Bottom line is you are fine.

Graufuchs

Well when I started it up i gota cloud of smoke but it went away after about 3 sec. turned it off immediately drained excess oil, restarted it and it runs fine. Just sacred the **** outta me.

theiceman

That is too funny ... but we do read about that a lot . I did something simialr when I first got my car . One day it just would not start for some reason, to this day I don't know why, just would not fire. I took the air filter cover off and lifted the plate to see if I could hear the fuel pump and I could. That night I recharged the battery and the next morning I turned it over for about 20 seconds , still nothing. One last try and I turned it over for another thirty seconds. I hard a faint cough from the exhaust so kept cranking . The coughing got more prounounced and eventually it started to run and I could take my hand off the stkey, out came HUGE plumes of Blue smoke... the neighbors thought my garage was on fire.
Eventually it cleared and to this day I have never had it happen again and I have no idea why it did. But definitelt gave me a big scare...

pjc

I think everyone who has worked on these cars has overfilled at some stage - if not they are a not being honest!

With an engine stood for so long I would as a minimum given it a full service and then churned her over with the fuse out on the fuel pump to ensure the oil was circulating and I had pressure - ie the light goes out on the dash. This would also give a clue to any potential issues - noises etc from the engine giving an indication of a mechanical problem.

Noises are noises and without hearing it, it's difficult to know what the problem could be - hopefully something simple.

Good luck.

PJC

theiceman

That actually is great advice

I have made it a habit on all my cars after changing the oil to pull the distributor main wire while priming ater changing the oil. than crank for about 10 seconds. Sure I dump a little fuel in but I can live with that.. Has never been a problem. I used to pull the fuel pump fuse but found there was always enouhgh residual pressure held by the check valve to start it .