3.6 conversion oil pressure question

[code7rpd]

I am still waiting on all my parts and my car is still in the shop so I am taking the time to tune up the 993 motor and change all the seals I can to prevent leaks. I have a question about the oil pressure and temp gauges. Here is the scenario:
The car is an '81 SC. I have the earlier oil pres. and temp gauge which reads 300 degrees for max temp and 140 lbs. for max oil pressure. I was told by Hollywood speedometer that the pressure sending unit from the 993 will work on the 140 psi guage but the temp won't. he can sell me a temp sender but needs the thread size. Does anyone know what the thread size for the temp sender on the 993 is? Also, do the 993 gauges read pressure up to 140 psi or does it have the non numerical type of gauge. I just want to make sure I have the right sender befire I out the motor back in!
Thanks!

[Bill Verburg]

You just need any pre '77 temperature sender. they are the ones that will read correctly w/ the earlier numerical gauges. If you had kept the oem '81SC gauge then the 993 sender would have given the correct readings.

The 993 pressure sender w/ an earlier gauge will just read 2x actual. I changed the temp sender but left the pressure sender because I like the doubled range of movement, never did look into what replacements might work and read correctly. ther is an issue w/ the pressure gauge in that it reports to 2 different places, I think maybe the gauge and the DME so you need to be very careful when changing it.

The tach will likely need an amplifier unless holywood can mod the existing one to read the 993 DME output wave.

Also be sure to do the power stearing seal(even though there is no pump) they are a potential source of leaks.

[pbs911]

What Bill said is what I experienced. I did, however, try to rectify the double oil pressure. I was unsuccessful. Ingo is working on getting me the right resister so I can run it in line to decrease the signal by 1/2 to get the correct reading.

[Moses]

My oil temp and pressure gauges from the SC work just fine with the 993. The tach needed to be replaced with a later one.

[surflvr911sc]

There are two senders for the 3.6, a 140 psi and an 80 psi. Seems to me the 80 psi seder should solve the problem since the early guages read 5 Bar, 73psi w/ change. Am I wrong?

[surflvr911sc]

Anybody know if this works w/ the 80psi sender & 5bar gauge or is it a voltage problem w/ the conversion?

[Bill Verburg]

I believe that the problem is that the oil pressure sender has 2 output circuits one to the gauge the other to the DME. If you modify the sender for the gauge then the DME will get a false reading.

[pbs911]

Mose, how did you get he oil pressure to work with the SC guage? Doesn't the 993 guage have 2 connections whereas the SC 1?

[surflvr911sc]

OK, sounds reasonable, but what does the DME do w/ the oil pressure input?

I actually thought that the extra output on the sender was for the oil pressure light and it replaced the low pressure sender on the top of the engine. I might need to study a bit more. It would be easier if my 3.6 was in my garage.

[Bill Verburg]

I was only able to trace it to the vehicle information module hence my inference that the DME used it.

I do remember several conversations w/ the technicians that left me w/ the impression that it was not going to be a simple swap of senders like the temp. sender.

Steve Timmins also mentioned the dual output and the adviseability of leaving it. For the life of me I can't remember the details.

[surflvr911sc]

More questions:

Why are there four different senders for the 3.6? There is the single style sender that comes in either 80 & 140 psi. Then there is the dual style that also comes in 80 & 140 psi.

What years/types use which?

[k9handler]

mine (140) reads at 2x...so I never thought of the (80) sender, that may be a solution otherwise I would just live with it.

[surflvr911sc]

I ordered an 80 psi sender a week ago b/c I thought that would take of the problem. Since I don’t have an engine at all right now I can’t say if it will work or not but I’m hopeful.

The only thing that’s bugging me is what Bill said about the DME. What would be the negative effects of using the wrong sender w/ the DME?

Kind of goes back to my question of what does the DME actually do w/ the input? Is it possible that it would have an oil pressure/rpm map that it would use for the check engine light? That’s all I can think it would use it for. Seems to me it would be simpler and just have a minimum pressure that would come off the low oil pressure sender. An oil pressure map seems overkill.

Which leads me back to my thinking about the low oil pressure sender. Does the 3.6 have one or did the dual sender replace it. I feel like I’m chasing my tail here.

[Speedster94]

the 2 connections are 1. for the Gauge and the other for the light ,
The DME has no connection for the oilpressure but for the Temperature .
This is another Sender right beside it .
Harald

[surflvr911sc]

Cool, thanks Harald. Then the 80 psi sender should do the trick.

Guys?

[code7rpd]

Does anyone have the part numbers for the 80psi and the 140 psi senders. I am not sure which one I have on my car. I also sent an email to Steve Timmons about the senders and I will let you know what he says.

[surflvr911sc]

I don't have the part numbers but I'll see if I can find anything. Also, I incorrectly said it was a 140psi sender when it's 150psi. Small mistake but I thought I'd point it out.

[code7rpd]

Just ouot of curiosity, are the 993 oil pressure and temp gauges similar to the SC unit in that they don't show numerics?