1979 Mercruiser 470 in a 1979 Sea Ray 192 open bow. Need Help Oil Cap

[Chossink]

Just picked up this boat a couple weeks ago. Past owner stated oil had been changed recently. I checked the dip stick prior to running. Oil had good color and was full. I have now run it 3 times on the water. Running great. Today when I went to take it out. I noticed the oil cap off and oil spilled all over the top of the engine. Dip stick was also lose. Everything looks fine BUT........ I can't for the life of me figure out how to get the oil cap back onto the top of the engine. I'm starting to feel like a idiot but it is not a screw cap or locking cap. It looks like a rubber stopper but it's just sitting there. Help please..

 

[Tnstratofam]

:welcome: Pics would help. Not sure how the cap is supposed to stay in if not a screw on.

 

[thumpar]

There may be some different types out there but the rubber "stopper" should have a ridge that keeps it in place. Maybe it is worn out or the wrong part.

 

[Chossink]

Ill get some pictures and post them.

 

[stonyloam]

It is a rubber stopper https://www.mercruiserparts.com/showSpecialPicture.asp?pn=807152

 

[SDSeville]

I guess it depends if you have the stock valve cover or not, but it should just be a rubber stopper that pushes in and is held in by a lip/ridge in the cap.

 

[Chossink]

Here are the pictures. Thanks for responding. It seams like a rubber stopper to me also, but it just will not pop on. What am I missing here? It looks just like the one stonyloam posted

 

[Grub54891]

Any auto store should have them,new. Its just a chevy oil cap.

 

[Chossink]

Thank you. Ok, what could cause it to malfunction and basically shrink cause it just sits there and has no firm seal.

 

[stonyloam]

I guess that time and heat could cause it to shrink a little. One thing you could consider, drilling a hole through the center of the stopper inserting a small carriage bolt and washer, then putting a washer and wingnut on top. Then when you stick the plug in, give the wing nut a few turns and that should expand the plug enough to hold it tightly in place. If the plug is hollow, that might not work, I just can't remember what mine looks like.

 

[Bondo]

I guess that time and heat could cause it to shrink a little. One thing you could consider, drilling a hole through the center of the stopper inserting a small carriage bolt and washer, then putting a washer and wingnut on top. Then when you stick the plug in, give the wing nut a few turns and that should expand the plug enough to hold it tightly in place. If the plug is hollow, that might not work, I just can't remember what mine looks like.

Ayuh,....... but it's only plastic,........ 'n 35 Years old,.....