oil switch/sender issue

[thedon809]

I'm having this weird problem with my oil pressure sender. I converted 85 glht to smec and used the later style all in one sender/switch. Is the L body cluster not compatible with the newer switch/sender? For some reason the light will come on and the gauge will just drop down to 0 when its warmed up even though I put a mechanical gauge on and it reads about 15psi hot idle (see video). I ghetto rigged the original old style single wire switch into it and the low oil light never came on. So I figured my sender/switch was bad, bought a new one but it does the same thing. As far as the gauge, it's almost like the new style sender has a much lower operating range. It either reads right in the middle or nothing.
http://vid272.photobucket.com/albums...psfmjinkcb.mp4

[supercrackerbox]

I would think they should be compatible, but I'm honestly not sure. For what it's worth, I've been through too many of those switches to count on my Daytona because of the same issues. They all seem to eventually leak oil in the end where the wiring plugs in and messes up the signal. How much work would it be to go back to the original setup? Might be your best option.

[tryingbe]

Buy a new style oil pressure sender and install it?

[thedon809]

I bought a mechanical oil pressure gauge from oriellys and it says I have low oil pressure as well. Maybe that matco oil pressure gauge is out of whack? I'm going to assume my oil pressure is indeed low. This really blows. All my bearings measured good clearance so I'm not sure why oil pressure would be low. I blocked off the balance shaft feed also. I have a melling pump in there. Think I have a used mopar pump laying around somewhere so I will toss that in. To top off the bad news #2 spark plug looked a little black. Sad day today. All I want is a good running car for once. In my 10 years of owning a TM I've never had a perfectly running engine lol.

[wheming]

What flavor oil?
Try some higher weight oil next change.

[supercrackerbox]

Did you use anaerobic sealer around the mounting flange of the oil pump?

[thedon809]

I used anaerobic sealer. I'm using 5w40 synthetic. Same results as 10w30. I know on my last engine I had a similar issue. On that engine I did 2 things at the same time and the issue ceased. Turned the crank and made a paper gasket for the oil pump. I want to say the gasket fixed it because I have seen engines with completely destroyed bearings have oil pressure.

[thedon809]

Did gasket on the oil pump and replaced the pickup o-ring. Sad day. I think the only thing left is either the oil pump or bearings I guess. The oil pump worked fine in the old engine though. Turn the volume down because my phone camera makes it sound like a Honda.

[going4speed]

you could try replace the oil pump spring

http://www.ebay.com/itm/191559204609....N36.S2.R2.TR4

[4 l-bodies]

Excessive side clearance on rods will hemorrhage oil badly between crank and rods and result in low oil pressure esp. at idle. Did you check side clearance of rods when you built engine?
Todd

[thedon809]

I didn't check side clearance but when I had the oil pump out I wiggled all the rods to see if there was any excessive clearance anywhere. Everything seemed OK. I'm deciding if I want to rip the engine out or not right now.

[thedon809]

Welp, multiple years have gone by and I finally tore the engine down.



Could my plug be leaking?

[Force Fed Mopar]

Is the oil restrictor still in the block where it feeds the head? If not, that's where your oil pressure is going.

[thedon809]

It's there. Think I'm going to get a new crank, new bearings, new Mopar pump and see what happens. This crank is already turned .020 so I guess it's junk.

[marc]

Just so you guys know, the later combination oil switch/sending unit is not compatible with the early dash gauges.
I went through this went I swapped the 89 Tll engine/SMEC wiring into my 86 Daytona and more recently on a Tll swap into a friend's 86 Daytona. I had to use a separate 86 sending unit and a 87 Reliant(I believe, I think the oil pressure switch pipe thread size changed in 87) oil pressure switch.

[going4speed]

I have an 88 single style sender in my 86 GLHS and it works a treat. Am I set up for failure here?

I get 3/4 pressure on gauge at start up and it drops to about a third when hot idle. Running 10w-30.

Verified these pressures with the old style setup prior to modernizing

[marc]

The 88 combination sender has a different part number then the 89 combination sender so it may work with 88 and down gauges.