What kind of reliability is had with the factory plugs? I'm sure it's spectacular when they fail, but is it really that often? Is replacing them with threaded plugs just going to let me sleep better or is there more to it?

Any response is appreciated.

Thanks,

Joe

Not often at all, but the cost of failure is high.

I had one fail and because I thought it was "just a gauge problem" I didn't believe the oil light and ended up with an engine overhaul. Mine failed on the coldest morning of that winter when the oil was thickest because the engine wasn't warmed up yet.

If you are doing an engine overhaul then replacing them with threaded plugs is something you should do - no question about it. If you can tell that you have a leak from one of the freeze plugs then you are living on borrowed time and need to do it soon. I understand that it can be done without tearing down the engine, but great care has to be taken to avoid metal shavings in the oil galleys.

I had one pop on my old 1.8, first cold start on a cold morning. I did believe the light, so no permanent damage on that one. I had the car towed to my mechanic, who Did Some Magic ™ and fixed it. I assume he put an oversized plug in, but I don't really know what it was.

--DD

My last 914 dropped a plug on the garage floor in the middle of a cold night. Weird.
http://www.914world.com/bbs2/index.php?sho...amp;pid=1106728

It is weird how they all happen when it's cold

Makes sense to me that it happens more often when cold because of thicker oil and higher oil pressure on cold startup. The strange thing about mine is it wasn't running, it dropped in the middle of the night parked in the garage.

My guess would be different materials between the plugs and the case and when cold, the plugs contract more than the case making them somewhat lose.


Yours was probably already backing out before it finally dropped.

The plugs are made of aluminum.
On our race cases I threaded EVERY soft plug, not just the main ones. You'd be surprised how easy some come out, I was.

Lose an engine to a loose galley plug and you'll take them seriously.

Jake,

That part is understood. I'm questioning their reliability.

Thanks,

Joe

Interesting you state that in your initial post

When I bought my car, the original engine had what looked like JB weld, or some sort of hardened epoxy over the galley plugs.. I am not running that case in my car, but is that considered even remotely strong? or is it pretty much a bandaid?

I mean, the goal is to prevent the plug from backing out. If it's epoxied in place, wouldn't that prevent it from ever backing out? I don't know, it seems like a cheap fix IMO, but it does seem to essentially fix the problem at hand..

Anything other than removing plugs, cleaning the galleys exceptionally well and then installing threaded plugs would be considered a band aid.
The fastest way to find your way to mechanical hell is by taking a shortcut.

Galley plugs, How often do they really fail?


Just once!

Given that we are talking about two different materials and a 40 year old motor...I suspect it has out lived its designed lifespan.

Rich

The galley plugs are aluminum.

how many different types of aluminum are you aware of?
Its two different materials...one is cast.

Rich

Ok, it's a moot point now. They're out from behind the flywheel, and they were pretty tight. Well, two were....

As far as I know there is only one "type" of aluminum. It is... aluminum.

I am aware of quite a few different alloys. And yes, I know that the case is cast of A356 and that the plugs are likely stamped from sheet aluminum, probably alloy 3003.

we agree, splitting hairs.
I was trying to answer his initial post...
How reliable...well its two different alloy blends (actually two different process's) that have been trying to hang on to each other for 40 years and countless heat cycles.
Similar issue with valve seats.
They are both a tight fit that relies upon friction only...and two different metals expand and contract at two different rates.
Two different alloys of aluminum expand and contract at different rates also.

For me, It is so cheap and easy to do, I just tap them all and replace them.
Seems kinda crazy not to do it.

From what I have heard and seen its not super frequent that it happens...maybe ten that I know in the past ten years....so its not alot.
But, its your motor..and your risk.

would I pull a motor just to replace them, no.
Would I do it while I am rebuilding a motor, absolutely.

rich

I couldn't agree more. Rather than fret about it, just yank them out and make the accepted modification.

All 5 plugs are now out. I can honestly say that the fronts adjacent to the oil filter hanger were going nowhere...but the slide hammer takes no prisoners. So next is the slow, deliberate task of reaming and tapping the holes..making sure no shavings get inside.

Yes, this would have been much easier during the rebuild but at least there'll be no concern in the future....

Joe

That was SOP for many years, put epoxy over them so they don't come out. I don't know how well it worked, but it was recommended by a number of people at one point.

--DD

If there are different "types" of aluminum I am sure that Len has welded on all of them. (and done it better than any other human I have ever encountered)

After 23 years of welding aluminum I do know my way around the stuff!