SBC Oil pressure sending unit HELP... stumped on this one!

C.Berry

C.Berry

Bad News
Joined
Aug 10, 2008
Location
Blacksburg, Va
Ok so just rebuilt my 80's k5 with 350 block 72 400 cast heads/manifold etc... Ok so never had leak before build now i have a oil pressure sending unit leak... ive tried teflon tape, permatex black oil resistant thread sealer and new brass fitting for the unit to screw into but the damn thing is still leaking oil... im wondering if anyone knows if there is another kind of fitting that would screw into the block that would seal up or if brass is the best the parts stores show a straight fitting but for my engine i must have a 90 degree fitting.. .any help would be great i hate the oil all over my new engine and not to mention its pricey!! Thanks fellas
 
retapping block is not an option at this point...
 
Nobody has anything to chim in???
 
It ain't the sending unit. I had the same problem on my 87 Suburban, and assumed the brass elbow was bad. It got worse and I looked a little closer...it was the gasket for the oil filter adapter. The piece that bolts into the block, were the oil cooler lines come out and the filter screws on. It was a tricky one to find, and a pain in the ass to fix, but I'd bet dollars to donuts that's where your oil is coming from. If you just rebuilt the engine, then either the gasket was damaged or left out, or the adapter isn't torqued down properly.
 
Yeah i know its the elbow for the sending unit... I watched it squirt oil up when revving the engine! thanks tho I actually replaced the elbow, sending unit also it was fine for four days then started leaking again
 
And to be clear i also work on mondays and everyday... Just happens to be my day of birth so i had plans that didnt consist of work and figured that most these guys are working and possibly online that someone might have an suggestion that i hadnt tried!
 
Try TRU-BLU by Rectorseal. It fixed leaks on brand new fitting that teflon tape and teflon thread compound couldn't.
 
I thought mine was, too. I could have sworn that's where I saw it coming from. If it's not that, though, then which joint is leaking? The block end, the sender end, or has the sender itself come loose where it's crimped? I've heard of that happening. And you sounded like you were pissed that nobody had responded in three hours. Sometimes it takes a while for somebody with some insight on the situation to notice it here. I personally appreciate that you don't get a lot of uninformative or misleading posts and chit-chat here, unlike some of the bigger boards. The ones that do post responses here typically seem to have some good info, you've just got to be patient.
 
are you using a mechanical gauge with the nylon tubing or the oem sending unit?
 
catfishblues said:
It ain't the sending unit. I had the same problem on my 87 Suburban, and assumed the brass elbow was bad. It got worse and I looked a little closer...it was the gasket for the oil filter adapter. The piece that bolts into the block, were the oil cooler lines come out and the filter screws on. It was a tricky one to find, and a pain in the ass to fix, but I'd bet dollars to donuts that's where your oil is coming from. If you just rebuilt the engine, then either the gasket was damaged or left out, or the adapter isn't torqued down properly.
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Catfish... Man, that adapter gasket gets cooked on there, dosent it? Easyoff oven cleaner soaked into the little bastard works good to loosen it up to scrape it.

Jason... The typical Autozone/Advance/etc... sending units made in Mexico are pure trash. Get one from NAPA or Chevrolet if its the sender leaking.

If its the threads leaking... Rare... Use PTFE paste sealant. Like Franks Red Hot Sauce, I use that:poop:on everything. You can get it in a small tube at a decent parts store.

Not dissing you, but what are you tightening the sender with?
 
You can also get the PTFE at Tractor Supply if your parts stores don't carry it.

Yeah, it was a bitch. Laying on my back, shit in my eyes, scraping at it with whatever I could get up in there! Not looking forward to doing that again!
 
catfishblues said:
You can also get the PTFE at Tractor Supply if your parts stores don't carry it.

Yeah, it was a bitch. Laying on my back, shit in my eyes, scraping at it with whatever I could get up in there! Not looking forward to doing that again!
Click to expand...

Cant get enuff angle on the scraper to do any good either.
Good news is, now that millions of these trucks have been crushed, Chevy updated it and made it a non stick teflon deal.:wtf:
 
i had problems with the compression fitting on some crappy supcrap gauges in my jeep leaking all the time. at the block and the gauge. im not sure if you are talking about it leaking at the block or the fitting though
 
my fix was an electric autometer gauge btw
 
Catfish nah not pissed just impatient really lol and this truck is my dd now so need a ride. Yeah this is only board ill go on besides grace really all the ppl on here are from what i can tell genuine ppl except few that hate life... Yeah its actually looking like its coming from the block end i used a pipe wrench for the fitting it was only way to get it to grip cause the fitting is not an actual nut! Im gonna reseal manifold and try the PTFE to see if itll work for me there alot of things on this truck that need tlc the PO was a half ass mechanic an screwed me now i own it... all good tho thanks for reply it is 18/27 brass fitting i used. Appreciate the help guys
 
You can overtighten it. You should be able to turn it just a little beyond hand tight. Basically, screw it in by hand until it's tight, then twist it with a wrench until it's pointing up. With the right sealant, it shouldn't leak. Hopefully, you haven't cracked the block where it threads in, but that's a distinct possibility.
 
Ive tried to keep the torque off of it cause i thought id break the fitting off in the block then id be screwed hopefully this will fix it
 
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