The Cessna 120-140 Association Forum

Hello 120-40 Club,
I need to replace my Oil Cap for my C-90 engine. Looked on Spruce and some of the others and didn't find one. Any suggestions?
2332V

The correct oil cap depends on which engine, what oil tank it has and what airframe the engine is mounted on. There are probably a dozen or more possibilities. I think Spruce used to carry some, but maybe no more. You my have to get it from Continental.

Somewhere I have a Continental document that lists all the correct applications. Let em know which engine and I can try to look it up for you.

If the dip stick has come loose, I've heard of folks riveting them back together. Also, Fresno has some small parts for repair.

John,
Thank you for your reply. I can post a picture of what I have. The engine is a Continental C-90.
Larry

7220 wrote: ↑Mon Sep 28, 2026 5:56 pm John,
Thank you for your reply. I can post a picture of what I have. The engine is a Continental C-90.
Larry

We'll need to know the dash number.
i.e. C-90-12F
i.e. C-90-14F and so on.
Also which size oil tank you have.
4 quart or 6 quart

Found the service letter. If you have the 5 quart tank the correct part is PN 649608-17.

If you have the 6 quart tank then I think you need PN 649608-9 but all they give is the tank PN, 50351 and I can't find a reference to that anywhere. I have a 6 quart tank that I'll dig out and see if it has a number on it, but I don't recall seeing one.

I have an O-200 with a 6qt tank. The current?? p/n of the tank is A50352A1 and the dipstick is 649608-18 I have a notation off to the side which states, A36040. (and a whole host of notes I don't remember writing )

according to my parts book this dipstick should fit all the models with a 6quart tank. C-75 through O-200B

TCM may have updated their parts list since I last looked into this and p/n's may have been revised. You may end up calling tech support?

V529 wrote: ↑Tue Sep 29, 2026 6:14 am according to my parts book this dipstick should fit all the models with a 6quart tank. C-75 through O-200B

Aren't they marked for minimum capacity, or something that is engine dependent? (Memory fails me.) The C75 has a different, lower minimum than the O200.

Also I would expect the part for a tail dragger would be different from the one for a trike. Then there's the Ercoupes with the stubby necks...

I'm moving this topic to the tech section...

Well those numbers on the SIL don't match anything I have. Mine is labeled for 6qt but when I put in 6qt and run it after an oil change it shows 5qt. I just live with it and keep it at 5qt. 0-200 with a 6qt tank. Number A36111 on the dipstick itself.

I did find an obscure article on dipsticks and sumps regarding Aeroncas. My number A36111 shows up in one of it's tables and is listed for 0-200's.

https://johnpropst.yolasite.com/resourc ... 20rev8.pdf

6643 wrote: ↑Tue Sep 29, 2026 7:52 am

V529 wrote: ↑Tue Sep 29, 2026 6:14 am according to my parts book this dipstick should fit all the models with a 6quart tank. C-75 through O-200B

Aren't they marked for minimum capacity, or something that is engine dependent? (Memory fails me.) The C75 has a different, lower minimum than the O200.

Also I would expect the part for a tail dragger would be different from the one for a trike. Then there's the Ercoupes with the stubby necks...

I'm traveling for the next few days. I'll get back on this when I return. You've brought up valid points that I don't have an answer for right now.