Mystery Part Appears in Engine Compartment

[Rich Stidger]

I hate it when this happens.

During a general inspection, I found this small item that appears to be a plug in the engine compartment pan on the intake and exhaust manifold side of my Volvo MD22L. It is unpainted so it wasn't installed on the engine prior to painting. I don't even know if it is from the engine. I have no apparent leaks and I have searched the engine for a corresponding hole and found none.

Please take a look and see if this looks like anything you have ever seen. The indentations on the top suggest that a tool of some sort is used to insert or remove this plug from it's home. There is a rubber o-ring that is installed on the part also.

This part may have absolutely nothing to do with the engine, so think outside of the box. Maybe it is a non-related part that was on top of the engine for eleven years and just fell off into the pan.

Very strange.

 

[higgs]

No threads so it is probably not from something that would be under any pressure. Also odd, that with the vibration on diesels something like this would be used. It will be interesting to see what those with more engine experience say.

 

[Skipper]

Valve?

Best guess:

Looks like some kind of tappet valve. The indentations might be where the valve actuator (manual handle or knob) sets on the top. When actuator locks\unlocks, valve changes from open to close or vice versa. Similar in operation to what you might find in a head pump wet\dry valve.

 

[Ross]

Perhaps a plug from a compass? I don't understand the indentations. Was it this clean when you found it? yes? then it hadn't been there long. If it had been dropped on the deck could it have rolled/bounced into the pan? Sometimes plugs such as that cover screws or adjustment points.

 

[RAD]

someone is F..k..g with ya, just like the old trick of throwing a clevis pin on the deck of a sailboat , serious thought is maybe it was sitting on top of the engine for ever and it rolled off and another thought is a thermos top?

 

[RAD]

Heat exchanger plug when it was new before it was installed on the engine?

 

[CalebD]

Initially I thought what RAD already said. You found something that looks like it COULD have come from your engine. If you don't have any leaks from the engine then I would not worry about it. Stow it somewhere in your curios section on the boat. Some day you may realize that it was the jack cover for some electronics part that is now hooked up. At least it is not a Clevis pin as that would be bad!
Don't assume that it is from the engine. How many times have you dropped stuff while working on or around your engine?
I cleaned out most of my bilge this spring. There were several battery wing nuts and other assorted bolts, washers and miscellaneous crap embedded in the muck I removed. The boat smells better now but still more crap to clean up under the engine where it will take my best foul mouthed contortionist imitation to clean up.
Do you know what is in your bilge? I am still finding out.

 

[Witzend]

The "O" ring would suggest seal, brass would suggest corrosive environment, the dimples would suggest turning, but no threads?
My guess is this is a part that was intended to have threads, but was never milled correctly which is why it fell out in the first place. It may have been installed to keep dirt out of an inspection or adjustment port, maybe for the injectors?

 

[Ron20324]

Maybe the dimples are for a retaining spring or such? Like for a pressure relief on the tranny?

 

[higgs]

No one has dealt with my initial response re threads. If this cap was meant to contain something that would be pressurized it would have threads. This rules out a lot. It could have something to do with an intake water pump which is under minimal internal pressure. It also could be a reservoir cap.

 

[Rich Stidger]

Was it this clean when you found it? yes? then it hadn't been there long. If it had been dropped on the deck could it have rolled/bounced into the pan? Sometimes plugs such as that cover screws or adjustment points.

Ross- Yes it was this clean, and it hadn't been there long. It was sitting in plain sight and I would have noticed it a week ago.

It does look like a plug of some sort. No threads, but a small o-ring.

 

[Rich Stidger]

Heat exchanger plug when it was new before it was installed on the engine?

What is a heat exchanger plug? My heat exchanger doesn't have any kind of plug on it, just bolts and cap screw holding it together.

 

[Rich Stidger]

No one has dealt with my initial response re threads. If this cap was meant to contain something that would be pressurized it would have threads. This rules out a lot. It could have something to do with an intake water pump which is under minimal internal pressure. It also could be a reservoir cap.

It doesn't look like it was supposed to have threads. I think it is safe to assume that it is a part that is used as is. The only thing that is also a brass color that is anywhere near and above where this part was found is a brass engine cooling petcock drain. But there are no apparent parts missing from this petcock.

Note that this thing is just 1/2 inch in diameter.

 

[SoSound]

How far out of the box?

I don't even know if it is from the engine. I have no apparent leaks and I have searched the engine for a corresponding hole and found none.

Could it have been left or dropped by someone else working on or near your engine? Could be that someone else is missing your found part?

The indentations on the top suggest that a tool of some sort is used to insert or remove this plug from it's home. There is a rubber o-ring that is installed on the part also.

Or the indentations could be there for an external retainer mechanism to help keep it in place (like on old brake cylinder/reservoir cap - or a Grolsch beer bottle "flippy"). Also could rely on a vacuum or other suction in conjunction with the shoulders on the top of the plug...

Dave

 

[Rich Stidger]

Could it have been left or dropped by someone else working on or near your engine? Could be that someone else is missing your found part?

Dave

Dave- Now that's a thought. The only thing that happened in the last few days is that the boat was launched. The engine compartment was open to expose the transmission end so that the yard crew could check my stuffing box for leaks. I had just repacked it before launch.

I will take the part and show it to them and see if they recognize it. Maybe they had it in their hand for some reason and dropped it in error.

I was really hoping that someone might recognize this item and be able to define exactly what it is and it's purpose. I suspect that it has nothing to do with my engine, but short of someone dropping this part when they had their hands in the compartment, there is really no way for the part to appear in the pan but falling or rolling from somewhere else.

 

[higgs]

After reading the posts here I have come to a conclusion. Someone, who does not like you, broke into your boat while you were gone and placed that cap there to torture you.

 

[RAD]

See...Higgs thinks the way I do, and when you show it to the yard crew there gonna say they been looking all over for that part

 

[Hermit Scott]

When I took apart my engine there was a bronze flangeless bushing in the bottom. I searched the manuals through and through and could not find where it could possibly come from. I actually had the thought that someone just put it there. Since you had people working on your boat that is a high probability.
The part I found actually went in the end of the starter. If you have the manuals, I would go page by page and look for that part. If I had to guess, I would say it is some type of freeze plug, or a plug that filled a hole for a sensor that was optional. If it came off your engine at all.

 

[Ron20324]

It's a widget. Heard about them in an old Rock Hudson movie.

 

[RAD]

They haven't made Widgets in over 40 years and the Fratastat replaced them and that doesn't look like a Fratastat