Run without engine mounted thermostat?

[Jeff Alton]

Any advantage/disadvantage to using a 964 thermostat cover (no thermostat) on my 3.4. I have the part here and was wondering if there is any use for it?

Cheers

[Rob 930]

Jeff,

I can't imagine why you would want to run without the factory thermostat as long as you have an oil cooler in place. There's not much downside, as long as the thermstat is working properly. It also may be that if you keep the cooler, use of the 964 thermostat cover instead of the thermostat may not properly direct oil flow through the cooler. (I'm not sure about this, though; you can confirm by looking at the hardware.)

The 964s did away with the engine-mounted cooler in favor of an oil filter console that filters oil coming from the tank into the engine. If you choose to install one (from either a 964T or 993), then you can (and should) use the 964 thermostat cover. I did this on my 930. I removed the cooler and thermostat and put a 993 oil filter console on the engine, along with the cover you have and some Smart Racing Products hardware so I could mount the console and plumb the engine to my existing oil lines. It works great, but of course I have to make up for that loss of cooling capacity up front. Another interesting benefit: the 964 thermostat replacement cover has two ports on it -- one of which can be plugged and the other of which works perfectly for an oil temp sensor if you decide to run EFI.

Rob

[Jeff Alton]

That was part 2 of my question! I am running efi and need to mount an additional oil temp sensor, so this would be good place to mount one!

Cheers

[ischmitz]

The oil filter console only came on the turbocharged 964 and the 993 NA and torbo engines. The NA 964 engines had no second oil filter and no thermostat in the block. The thermostat was dropped when the on-engine oil cooler was dropped to make room for the PS pump.

The thermostat in the block is used to bypass the on-engine oil cooler during warm-up. Without it the oil will take a lot longer to warm up to operating temps. Your choices are to live with longer warm-up times or remove the oil cooler from the engine.

Ingo

[DonE]

I have a 930 and can tell you that it only takes a couple more minutes (max) to warm up compared to not having the engine oil cooler and thermostat. Before anyone says the turbo is different, I say its not until its warmed up. The fender well thermostat does a good job of recirculating the cool engine oil until its up to temp.

If you are using EFI, then this is a moot point unless you like to jump on the throttle early.

[Rob 930]

Ingo,

Thanks for the clarification on some of those details. It's true that for the 964 series, only the 964T had the oil filter console, not the N/A 964. What I'm still not sure about is this: If you remove the thermostat on an earlier engine and replace with it with a 964 thermostat cover, but you retain the engine-mounted oil cooler, will all the oil that flows through the engine be directed through the cooler, or might some of it bypass the cooler? As I said in my previous post, I can't imagine why anyone would want to run in that configuration, but if they were to do so, I would want to make sure they didn't also suffer the consequences of reduced cooling capacity with the thermostat removed.

Jeff,

Below is a photo of what I did on my 930. I obtained a used 993 oil filter console (which has the filter oriented vertically), and I bought the thermostat cover and various adapters and pipes from Smart Racing so that I could mount the console and use the stock "S" hose from the oil tank. I had to do some sheet metal mods as well to contain the cooling air in the absence of the oil cooler. In this photo, you can make out the thermostat cover with my oil temp sensor for EFI -- it's the one with the blue plug. The temp sensor is a Bosch unit, and it threads into the existing hole in the thermostat cover. The other hole in the thermostat cover is plugged -- with a part from Smart Racing as well.

Note that the 964T oil filter console is slightly different from the 993 -- it has a 15 degree tilt to aid in removing the filter. Though that's nice, it's a lot more expensive than the 993 version, and I can get the filter off just fine with the 993 console. What's shown is a 944 oil filter, which is just like a 993 filter except a bit longer; this makes it slightly more challenging to remove and replace, but I have a stash of 944 filters so I'll just use them.

[ischmitz]

[QUOTE]Originally posted by Rob 930
Ingo,

What I'm still not sure about is this: If you remove the thermostat on an earlier engine and replace with it with a 964 thermostat cover, but you retain the engine-mounted oil cooler, will all the oil that flows through the engine be directed through the cooler, or might some of it bypass the cooler?

I belive the thermostat act like a switch. When it's cold it simply blocks the flow to the oil cooler. When its open or removed it allows flow.

[Steve@Rennsport]

Yessir,..thats correct.

If one removes the thermostat and retains the engine mounted cooler, one must be VERY careful to warm the engine at low revs to keep from popping the cooler,...

[cstreit]

I've always wondered about that because while the cold oil certainly generates more pressure, are any of the bypass pistons in this same circuit? If so, then 5 bar cold is no different than 5 bar warm... If there is no pressure bypass, than that's different...

[MBEngineering]

HI if you do take the stat out and remove the oil cooler, to fit a oil filter housing, you will require a 930 107 767 02 HOUSING not the 964 101 768 00 housing as the 930 one directs the oil through the cooler, and the 964 dos' not. the 930 is £21.89 and the 964 is £15.31, both have the same top.

regards mike

[ekessel]

Mike,
Are you sure they are both the same on top? I think the 930 housing is tapped for an M12 fitting where the temp sensor would go, while the 964 is tapped for an M14.

-Eric
90 C2 (with the 993 filter console, but still untested)
NER/PCA

[MBEngineering]

HI that's right and slightly different angles on both tops for the senders, i have both sat hear on the desk now, to look at, before i fit to turbo one to the engine with the cooler removed to fit the filter housing in the photo (3.0Lt engine, has a 935 oil stat blank in at the moment)

regards mike

[Philippe Roger]

Hi,

Does someone have the reference/where to get the highlighted connector?

Many thanks,

[scootergt3]

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