crop dusting again....can't take it...
 

finished a perfect rebuild on my 1974 914 2.0.....no problems everything is great....what the *&#@^....oil under the car...the oil sending unit...you know..the round plat that it screws into...a leak out of the bolt hole.....okay....drain all the oil out....pull the plate....fix it..seal it....put it back together....check it a few days later......look again....oil.....get back under the car...take a close look to see what i missed....a small drop is hanging from a pushrod tube.....start the car i'm crop dusting....on the other side of the drip......how can two pushrod tubes leak.....everything is new and fit perfect......okay....tell me the truth....my car will always leak....no matter what i do.....:( :( :(

yes.

I have 2 tubes with a small leak, and only when under pressure. I think I'm pretty lucky - it was the first time I ever took apart an engine and put it back together. I had decided against any additional sealer on the tubes, based on advice from several people on the list.

(knock on wood) i put a thin bead of silicone sealant (reddish colored) on the o-rings when i put my 1.8 together. dry so far (where is that wood.....)

jam,

if you change out the pushrod tube seals with the Biton ones, you wont have to use sealant and they will not leak

I had the same experience after a rebuild. The leak on each side appeared to be from a pushrod tube, but both turned out to be form the valve covers. They continued to leak no matter what I did, until I used Gasgacinch to glue the "CORCK" gaskets to the valve covers "ONLY". Not a single drop since.

My limmited experience:
I was told to smear moly grease on the valve cover gaskets (both sides) before install.
For the push rod tubes I always use the newer, oil proof Viton seals, and some sealant. I just used Hylomar, but used to use something called 1109, or some other number. Generally you want it to be high temp, oil proof, and non hardening.
All of these things worked for me thus far.

This problem was one reason I did a 2.2 six conversion. A major job that wasn't cheap, but no more leaks (okay, well some little leaks, but I have the six which performs great, sounds awsome, and looks terrific). The six actually fits the car much better than the four -- much cleaner. The project is not for everyone, but it was a lot of fun : )

Regarding the Viton O-rings on the push tubes. As the engine heats up and cools off, the push rod tubes MUST be free to slide freely back and forth to cope with engine heat expansion. A fully warmed up engine is at least 2 or 3 mm wider then a cold engine! If you use silicone adhesive to seal up the O-Rings, it prevents the tube from working as intended. It will work for awhile but eventually the leak will return. A better choice of sealent available for this task is Dow Corning #55 O-Ring Lubricant. It is silicone based grease, not an adhesive. It handles the high temps without melting or flowing and it never drys out. It doesn't limit the oil tube from moving back and forth freely, in fact it makes it easier to do so. The #55 lubricant is funny looking, just imagine a purplish colored grease!. Be sure to use Viton O-Rings, the original rubber O-Rings harden up with age. I bought my Dow Corning lubricant at a Grainger Inductrial Supply house. It had to be special ordered.

Lastly, the molded rubber rings which are used to seal up and mount your oil cooler to the engine block will sometimes leak and drip oil down onto your oil return tubes and then down onto the heat exchangers. So check the bottom of the oil cooler for evidence of fresh oil to see if this is happening. Was your oil leak located under the oil cooler?

Good luck Lyle

no...the leak came from the push rod tube...i took off the heat exchangers to get a good look....i was thinking about building a skid plate with a small catch at the end to collect the leaking oil....but i thought this would make the engine run hot....i'm still working on the design.............:D

Just repair it...Don't bandage a symptom.

The conventional method of sealing the seals does not work. It took me 5 solid years to be able to seal these engines up tightly, now I can dyno one for 8 hours and she'll be dry as a bone!

What i have heard from several people is that you want to clean the insides of the pushrod bores as clean as possible on both sides of the engine case and head. You do not want to use any sealant on there at all. You need to let the seals expand and contract with the engine.