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Posted by: mlindner Jan 29 2020, 03:42 PM

A friend of mine has a 74 914-6 GT Tribute with a 2.7Lt six. If not driven for a few days/weeks the oil will drain down into the engine. I do realize the oil tank is higher than in a 911, but what is the answer. Thanks, Mark

Posted by: Steve Jan 29 2020, 03:45 PM

I’ve heard that comment before, but I have not seen any issues with that in my 30 plus years of ownership. No additional leaks and the normal puff of smoke on startup, which is the same as a 911.

Posted by: mepstein Jan 29 2020, 03:47 PM

Rothsport oil check valve


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Posted by: rgalla9146 Jan 29 2020, 04:13 PM

It is an unusual 911 or 914 6 that that does not smoke a bit on start up.
Oil level is checked on both models at operating temp on flat ground at idle.
If migration of oil to the crankcase was a problem Porsche had thirty plus
years to correct it.
Finding no oil on a sleeping 914 6 dipstick is normal.

Posted by: 914Toy Jan 29 2020, 05:00 PM

Posted by: flyer86d Jan 29 2020, 06:07 PM

The system is “wet sumping”. Harley Davidson motorcycles do this also. I have been told that this happens when you use a non factory oil filter that is missing or has the incorrect check valve. I haven’t had the problem in any of my 911’s but I always use factory oil filters. I’ll bet that a few engines have been “ rebuilt” because of this like the ones that smoke on start up as the all do. Hell, my Boxster occasionally smokes on start up. I guess I’ve been playing with these things too long........

Charlie

Posted by: Jett Jan 29 2020, 07:10 PM

We have two 911’s and they both smoke on startup after a few days of not driving.

Our mechanic\friend has many Porsche certifications and wrenched on them for 30+ years... I asked if the smoking on startup can be fixed... he smiled and assured me it was expected, but I believe at the time he was offended that I implied a perfect running car needed to be fixed

Posted by: Rob-O Jan 29 2020, 08:54 PM

I think we’re missing the point. The point is, are those check valves really $300 fuching dollars???

Posted by: RickS Jan 29 2020, 10:28 PM

When I bought mine it was less than $200 and i still felt like I was being soaked. But the thing does work.

Posted by: Mark Henry Jan 29 2020, 11:17 PM

Deja vu, I started a thread about this a couple weeks ago.

Posted by: raynekat Jan 30 2020, 01:32 AM

There is some thread over on the Pelican talking about these check valves.
Seems they are more sophisticated than a "standard" check valve.
Do a search over there and perhaps you can locate the thread.
All that buy/use them, swear by them.

That said, I don't have one on my 911 or 914-6.
The smoke at start up just tells me I have a flat six with a dry sump oil system.

Posted by: mlindner Jan 30 2020, 05:30 AM

The problem isn't so much smoke on start up, it way to much oil in the engine. Like filling it up. He's thinking of draining the oil for winter storage.

Posted by: 914forme Jan 30 2020, 06:34 AM

Is he afraid of hydro lock?

I think the solution besides the $300 or a valve you will forget to turn, or gets turned by some object and ruins a perfectly good engine, is the fact that the engine needs turned. So fire it up every so often and live with it, does it some good.

If he is worried about hydro lock, run minimal oil in it. And flag the steering wheel with something big that reminds him there is no oil in engine! To many times I have seen people forget this detail and start an engine, including myself It only takes once. Pull the ignition so it does not fire when he turns it over.

Long term storage, requires so much more. If he is draining the oil, then I would fog everything. top side crank case, oil tank. Seems like a huge pain, but I do it every fall for my water bound money pit.

Posted by: ClayPerrine Jan 30 2020, 08:08 AM

Years ago, Wes Hildreth (RIP) built a 914/4 with a dry sump system using a /6 oil tank. It was great on the track, because no matter how hard you cornered it, it would not lose oil pressure. The downside was the sump would fill up when it was parked. It would smoke like an SOB on cold startup, sometimes to the point of making people ask if the motor was blown. Once it was running, it was clean as a whistle.

The bottom line to this is any dry sump system will drain oil back into the sump. How much it does is determined by the tank placement. There has to be some downhill run from the tank to the engine so gravity can initially get oil to the pump. If you don't have that downhill run, then the oil pump has to prime itself at every startup, and that will cause extended time running without oil pressure on startup. Not good.

So we live with the smoke on startup.

Posted by: morgan_harwell Jan 30 2020, 09:32 AM

Yep. And it works.
I installed one on my 914-6 conversion a couple years ago after it started to hydro-lock.
Start-up smoking greatly reduced, too.

Posted by: Cornerlot Jan 30 2020, 10:15 AM

The 997 uses an oil return check valve PN. 997-107-491-91

Not sure of the hose size, but its only $70 online. Might be an alternative.

Posted by: porschetub Jan 30 2020, 02:04 PM

Its not an issue and is normal,I get a small amount of smoke,generally after the engine has sat for a week or more.
From reading on Pelican it appears folks with a lot of smoke often had overfulled tanks or not checked the level with the engine running ,IMO that's worse than being down on the level.
Don't see the need for the non-return valve but it can't hurt.

Posted by: 914forme Jan 30 2020, 03:11 PM

It it is Aluminum hose size might not matter steel not my favorite but can still me modded to work.

Posted by: sixnotfour Jan 30 2020, 03:33 PM

DANGER.... NOT THE CORRECT VALVE !!

Posted by: sixnotfour Jan 30 2020, 03:38 PM

THIS THE ONE....
If your pretty handy , the Porsche part is $125, needs some creativity = time=$$

https://www.911partsdirect.com/shop/996-99-04-3/gt3-gt3rs-996-99-04-3/engine-components-996gt3-997gt3-oil-inlet-check-valve-metzger-motor/


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Posted by: sixnotfour Jan 30 2020, 03:57 PM

http://willhoit-auto-restoration.mybigcommerce.com/wr-anti-drain-back-valve-for-porsche-911-up-to-1989/


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Posted by: JmuRiz Jan 31 2020, 10:35 AM

I was thinking the same thing....also it's a shame the parts I see are $300 for a simple valve...Porsche tax for sure.