View Full Version : Need help sourcing T-fitting for V-drive oil drain system (2007 Moomba LSV)
meech
07-18-2025, 05:30 PM
Hi all,
Hoping someone here might be able to help.
I'm trying to replace the T-fitting that connects to the block on my 2007 Moomba LSV with an Indmar 325 Assault engine. It's part of the V-drive oil drain system.
My old oil pressure switch snapped off during removal (of course), leaving the threads stuck inside the T-fitting. We weren't able to get the broken threads out, so now the whole T needs to be replaced. I have the replacement oil pressure switch (I was trying to swap this in), just can't find the right T-fitting anywhere.
This has turned into a bit of a mess, and I'm hoping someone here has dealt with it before or knows a source. I've emailed Indmar and Skiers Choice but figured I'd ask here too.
Photos: https://photos.app.goo.gl/KEPX9cXc9mCYLEzs9
I really appreciate it - Thank you!
Holdmybeer
07-18-2025, 08:25 PM
oil pressure sending unit tee.
Search this exact thing and you will find all kinds. You need to know the thread size and type.
1/4" NPT is typical for GM which is the basis for that Indmar engine.
If you have a good auto parts shop or engine shop near you they will have one in stock for $20
meech
07-18-2025, 10:24 PM
Thanks @Holdmybeer - I really appreciate the quick reply.
I looked into the 1/4” NPT tee options, but my setup seems to be a little different. The fitting that screws into the block is actually a compression fitting that sits inside the bottom port of the T, not threaded into it like a standard NPT. The T-fitting itself has to accept that compression fitting on the bottom (then the T screws into the block), with the side ports going to the oil drain hose and the pressure switch.
So the generic NPT tees, I don't think, will work...? I'm a novice on all of this, so learning as I go. :)
I’ve posted some photos of the original assembly here: https://photos.app.goo.gl/KEPX9cXc9mCYLEzs9
Thanks again for your insight/thoughts on this.
Holdmybeer
07-19-2025, 07:58 AM
The part you are looking for is called
"Oil pressure adapter fitting"
Your engine is based on 1996 to 1999 GM 5.7 V8 engine. A similar adapter is installed on the trucks from this time.
You are correct a normal tee will not work. However, I am curious how the compression stays in the bottom of the tee while you screw it into the block. Are there threads internal and external on that port? Does it just sit in there?
meech
07-19-2025, 10:51 AM
Yeah, the compression fitting threads into the inside bottom of the tee, and then the whole thing screws into the block. So that port has internal threads and the compression fitting screws in and then just sits in there. Definitely doesn’t seem like the average T-fitting, which is what’s been tripping me up.
Any chance you know which Oil pressure adapter fitting I need?
Holdmybeer
07-19-2025, 01:05 PM
Not sure exactly which one will work for you.
GM block is typically 1/4NPT into the engine. The oil line is 1/4NPT with a reducer for the compression. The pressure sending unit is 1/8NPT.
You need a male 1/4 female 1/4 female 1/8 adapter. The internal threads on the male for the VEEJET nozzle is the hold up. Never seen a spray nozzle installed in a oil return line. That is either to make the gauge read higher oil pressure (hack to hide problems) or being a boat helps spray and lubricate the camshaft in the middle of the engine. Never seen that and not 100% sure if you could go without it installed.
meech
07-19-2025, 01:24 PM
Appreciate all the info. Honestly I'm stumped at this point. None of it sounds good, and I'm not sure where to go from here. :-|
Do you happen to know if anyone from Indmar or Skiers Choice is active on these boards? I've reached out to both directly but figured I'd check in case anyone here has a direct line or insight.
Thanks again for all the help.
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