Hi all,

I have recently replaced gaskets, oil temp sensor and the "taco" plate on my '73 1.7. My central console temp gage was not working.

Now, not only the temp gage still not working, but I am facing a major oil leak which appears to be coming from the sensor wire rubber boot on the taco plate.

I took care to properly install the components ("red" oring, paper gasket and "crush washer" on the 2 retaining hex bolts) in addition to tightening them well as spec.

Before I attempt to retry this experience (I will need to drop engine oil again!), wondering what could be the problem:

1- for the temp gage still not working...
2- for the bad leak I noticed...

I heard that the sensor must fit the gage... I don't know if I have the correct part number.

Also, wondering if the sensor threaded coupling welded on the taco plate is supposed to be oil proof? There are only a few welds and so I assume that the oil can seep between the threaded part and the plate and escape through the boot.... My theory.

Thank you very much for your thought and comments!
Sebastien

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This is a common leak point. A poor design from Porsche. Must have had the intern doing this design.

The rubber boot isn't the problem, it's just the exit for the oil coming through another leak point.

I finally fixed my leak by adding a paper gasket between the plate and the case. I cut it out of gasket material from FLAPS. The gasket must seal around the fasteners. An old Porsche mechanic told me that the factory added this gasket, but he's never been able to find it in the PET or buy it from the dealer.

I will be waiting for the solution on this since mine leak also after replacing the gasket. thank you @rivs914!

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Is it not 039101287 ?


https://content.eu.porsche.com/prod/pag/cla...1258185002922CF

I though my sensor plate was leaking, so I got a new one from Porsche. I had 2 O rings from engine gasket kit. BOTH are over size in my opinion. Had to wad O ring in to hole. Used teflon tape on temp sender. Put it all together and two days later, back to the same small leak. I think it is the O ring causing the problem.

Most of the time it leaks because someone has stripped the M6 case threads.
Like the 5 galley plugs SOP for my rebuilds is both the M6 taco plate holes get a heli-coil.

It *is* a terrible design. The outer o-ring likely seals fine but then you have the seals around the bolt holes that'll leak, given it does not seal between the plates.

I've often thought about leaving the bottom cover off, and putting o-rings (or better copper washers) under the bolt heads directly to the upper plate. I'm not convinced that it would make the sensor head any more vulnerable to road damage. I also doubt that little cover does much beyond keeping the wires from hanging down and I can weld a harness-holder directly to the upper plate.

Good find - this is correct, isn't it?

It's here too, in case you want to know how much before ordering. https://www.pelicanparts.com/More_Info/0391...039-101-287-OEM

Yes! That's the gasket. That solves the problem. Cool to know that PN.

Also, to another post in this thread, you shouldn't need any tape on the sensor threads. The copper crush gasket addresses this leak path.

Thank you all, good to know that I am not alone with this issue! If I understanding right, the "special" gasket that goes directly on the engine looks very similar to the "paper one" going between the plate and the cover? Is it the same? Could I use Permatex hi-temp liquid gasket instead?

And what about the seal between the threaded part and the plate that does'nt seem to be very "leak free"!!!?? That is a direct path between oil and cover where leak can occurs from wire boots...

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The oil temp sender threads into the plate from the opposite side of your picture.
The sender has a copper crush washer the seals the sender to the plate.

From your picture view the oil can get to the threads and the sender body but not past the washer.

That is the theory anyway.

Jim

That does LOOK like a leak path, but it really isn't, if the crush washer is installed correctly. The crush washer on the sensor seals up this path by blocking the leak path at the sheet metal.

COULD you use permatex? Sure.
SHOULD you use permatex? No. Do it right. Use the gasket.

The key to solving the leak is a gasket that seals around the fasteners. If the gasket doesn't completely encircle each fastener, it won't work. The gasket must be located between the sensor mounting plate and the case.

If your not concerned about originality, just replace it all with the billet aluminum replacement sold by a member vendor here.

I battled leaks in this area for years...no more leaks with the bullet plate.

Well that's awful rude...tease us and leave us?

LOL!

I'm technically challenged posting links using my phone. Google "914world.com billet taco plate" to find it. Its offered br username 914werke.

Great product.

Ah, ok it's Rich.

http://www.914world.com/bbs2/index.php?showtopic=342242

How far down does it stick?

Not really any further than the OE unit with cover installed.
When discussing the use on his engines with Jake he raised the concern of air flow over the sensor affecting the gauge reading so I sourced a cap thats now included

Thanks, Rich.

Any chance you offer one that's just a block off? Race car doesn't measure oil temp there. I could easily use the upper plate and just plug the hole with a bolt...but it won't look as spiffy.

I do offer as an option the plate alone. HERE
Typically offered for the owner with the issue this thread addresses.
They can use their OE sender & just replace the "Taco" plate & cover.

THanks, Rich. That's still machined with the threads for a sensor, yes? I was curious if I could just get a flate plate, no hole for sendor.

No biggie, that one will do the same function -- with a bolt in it.

Most type 4 engines have just a steel plate with no hole for the sensor.
Usually seal well with just the o-ring & copper washers.

Jim

@GregAmy It is.

Jim In fact IIRC the OE blanking plate is a bit thicker steel than the stock taco plate.
But, if you after a cover of the same material/expansion rate as the case ...