Oil Gallery plug FAIL

Anyone seen a failure like this before ??
Ran 4000+ miles / 15 months just fine, then it let go at 80mph on the freeway two nights ago. Dumped all the oil instantly, sudden loss of oil pressure, got it shut off within about 5 seconds, but I fear the worst.
Turbo (GTB2260) seems to have survived it, so maybe there is hope ?
I have to go out of town for a week, so it will be next weekend before I can pull the bottom end apart.














I dug back through my build photos from 2013, you can see the plug fully, correctly installed here. No idea what I did wrong, but I need to figure it out before try again !

Did you have the plugs out and replace them or are those stock? I'm assuming they were out for the rebuild?

Yes, plugs were replaced. Machine shop knocked them out to wash it after boring and honing.
I fitted new ones (genuine VW, from the dealer) when I rebuilt it. Used the same method I have always used, tapped it in with a socket that matches the largest diameter. I was taught to avoid pressing them in with the inside face, as this can deform them and reduce the interference.

Really depressing, a $1 item has likely killed $5k of work.

Your engine is probably fine since you shut down so quickly. It takes a bit of running for the bearings to start overheating, it won't happen instantly. If your turbo survived then the rest of the engine is almost certainly OK, the turbo is far more vulnerable.

I had something similar happen on my old 1.6TD. A chunk cracked off the intermediate shaft seal and drained the oil. As soon as my oil pressure alarm triggered I shut down, coasted to the side of the road with a rainbow sheen following me. Had it towed, seals replaced. Drove for years afterwards with no problems.

Charlie - I agree with vanbcguy in that you're very likely just fine, but pull a couple caps to verify.

I'm sure there will be a hundred suggestions as to how to put it in better/different/etc so I'll start it off

Maybe you could stake the OD with a center punch at 3 or 4 locations around the perimeter to give it a bit of a mechanical edge to catch on.

Another suggestion might be to use some red loctite on the next one you install

Might be worth it to check any other ones you have installed for leakage/looseness.

I'm betting that everything is fine inside though. I'm interested to see the top half of your rod bearings though

Based on the top pic, it stayed in the hole right?

Maybe build retainers that utilize the threaded holes nearby?

Had the same thing happen to me, but with both plugs came out. I turned off car as soon as oil light came on. It lost pressure when plugs fell out but still had lots of oil in engine, it only dropped pressure and not run dry.

I managed to replace both plugs, what a pain. I used shellac and taped them in good and deep then covered with RTV. I needed to cut the front crank seal housing in order to expose seal, not fun. Been running 15K now without any other issues.

I am sure you are fine.

I work in the diesel reman world and we use green loctite to retain the plug locked in place. Without the loctite the plugs come out sometimes.

Wondering if there's enough meat to tap the holes and thread in pipe plugs?

That's what us old air-cooled VW people do as a matter of course during overhauls...all the pressed-in plugs get ditched and replaced. 80+psi against those disks is a fair amount of pressure, and yes when they go it ruins your day quickly.

I couldn't find anything in a cup plug 14mm or 9/16" locally, so I turned some discs on the lathe and hammered them in. They were TIGHT, so hopefully I don't have the same issue...

Thx for all the replies, and ideas.

Jon, the timing belt rear cover (plastic) held the plug in place. Once I took it off the plug was completely loose, fell out by hand. I suspected this was the case as the direction of all the oil leaks were from behind the TB cover. TB was flooded.

The VW head (aluminum) uses ball plugs, and have 4 peen slots to ensure they cannot come out. Not sure if I could do the same to the cast block, I doubt it. I would also be worried about creating an uneven seal, and thus oil leak.

Unfortunately there is no easy way to tap the ports, there is a cross drilling to the #1 main right behind the plug, you can just see it in the photo.

The Loctite is a good idea, I wish I thought of that 16 months ago!
There is no easy way to pressure test these plugs either, and once the TB back plate is on, there is no way to tell if they are leaking.

Curious Chris said:

I work in the diesel reman world and we use green loctite to retain the plug locked in place. Without the loctite the plugs come out sometimes.

Click to expand...

Thx Chris, I will look into the green loctite.
What is the CORRECT way to install these ? tapped in with a socket/driver on the largest diameter ?
and what is the correct way to remove ? do you clean up the bore before installing a new one ?

Fix_Until_Broke said:

Charlie - I agree with vanbcguy in that you're very likely just fine, but pull a couple caps to verify.

I'm betting that everything is fine inside though. I'm interested to see the top half of your rod bearings though

Click to expand...

Thx FUB. No point speculating, I will know for sure next weekend when I pull the bottom end apart. However I am expecting the worst.
The "minor" detail I missed out in my earlier post was that I had just done a 2000-5000rpm WOT 4th run, EGT alarm went off at 1700 and I was coasting down from it busy watching 4 things at once. The oil alarm then went off, it took me a moment to figure out what it was over the EGT alarm and then I had to fight my way over 6 lanes of freeway to the shoulder, dodging two tractor/trailers. Crappy timing, so it was several seconds before I dared to shut it off, there was a lot going on. I had the clutch in to stop freewheeling the engine and I honestly do not know if the engine stopped before I switched it off.

So.. we will see. The head looks fine, cam bearings are worn but no spalling. Wear is expected with these loads.
The turbo is fine. I swapped in the old BEW on Saturday (glad no one bought it, it has been for sale for 6 months !). Fitted the GTB onto it, and fired it up for a few mins. Turbo spins freely and no leaks on turbine or compressor side.

I am curious about the rod bearings also... :-0

2 new engine builds for me did that, one of the the exact same colour as yours! tapped in with a socket

Usually they pop out on idle on the first start, after that we locktite them in place.

Next build will be tapped and use a grub screw i think.

BTW, one of the less mechanically minded guys here drove 30+ miles with no oil pressure when the balance shaft failed on his CR140, the low pressure light did not work, only had the oil level amber warning.

He got concerned once the turbo started to whine due to damaged bearings.

New oil pump and back to 240+hp!

Fwiw, in 2003 i had a similar oil loss event. I was on the nj turnpike late one night. While blasting up the road from 55, under full load, i noticed a weird film on my back window, was like, huh, its not raining.... Then, while I was still at full throttle when the oil light came on. I put it in neutral, then shut it off and coasted to the shoulder. Turned out my bypass oil filter had spun itself loose!

I fixed it, and drove that engine for another 150k miles. It always used oil after that. When i tore it down (wouldnt hold head gaskets anymore) nothing looked out of the ordinary bearing wise so i suspect oil usage was due to valve guides and seals, or turbo.

Good info to use for the future...

I would thread it and modify the plug to not restrict the oil passage. By adding relief cuts around it or to shorten the plug length to allow clearance, installed with red loctite or with green sleeve retaining loctite.

My engine machine shop usually installs the plugs with shellac sealant and peens the surface around the plug to keep it from blowing out. The only problem that he has seen from this method is that one was actually sucked into the block, but that was for the coolant plug on a rather built 468ci roller blower motor.

Another fix would be to use a retaining piece of steel that goes across the plug to keep it in place. Perhaps drill and tap two small holes around the plug and use panhead screw heads to keep it from packing out for extra reassurance.

I don't think retention is the issue (the plug was retained by the timing cover). Keeping it sealed seems to be the more important thing in this case.

The OEM plugs are nearly hopeless to get seated correct
I always make steel plugs on my lathe and hammer them in
Around 0.10mm press fit and they never fell out

The loctite green that was referred to is either 620 or 640 "sleeve retaining compound". I used some to fit loose differential carrier bearings onto a center chunk. I was told by someone that rebuilds many diffs to never plan on getting them off again.

Pretty sure I have a bottle of the stuff sitting in my parent's garage in Houston too.. though it is about 8 years old.

Thank you again for all the replies. I wish I knew all the above 16 months ago, could have saved myself a lot of pain.

Ordered some 620 today, will see how it works.

I see that this happens often, I was going to post it when it happened to me but I was embarrassed and was thinking I must have messed up.

I too wish I would have known when installing plugs, would have saved tons of grief and time.

I've never had a plug come loose or leak.After going through this thread we have since made modifications to keep the 3 plugs from moving on my engine.Thank you for posting your experience !

Are you using the BRM oil pump sprocket ? I noticed that the BRM sprocket would easily spike the pressure even when the oil wasn't cold.I went back to the old sprocket to avoid excessive oil pressure at any given rpm hot or cold.

Good point Andy, yes I have the BRM sprocket.

The pressure regulator is in the oil filter housing, so maybe the BRM sprocket drives the thing quick enough that at high RPM it moves more oil than the pressure regulator can flow. 'We' are commonly running engines quite a bit faster than the factory's idea of a proper redline at 4750 or whatever. Fixed displacement pump and all...

The pump's chain is a standard 8mm ISO chain, IIRC. When I was fiddling with mine I tried to find an intermediate sized sprocket to use instead, but I could not find anything in stock like you can with standard American sprockets and chains. Reminds me of a story my dad had of visiting Germany. He was going to build something or another and went all over looking for a place to buy lumber, could not buy 1x2 boards, or whatever metric equivalent. You simply did not buy boards in that town. You called up someone else and they would make what you wanted. If I wanted a sprocket, I'd have to call up a machine shop and have them make it. There is no "on the shelf" or using preexisting parts, it just simply does not occur to them. Much like purchasing anything on credit, you just did not do such a thing in Germany.

Yes, mine is the BRM sprocket, has to be as I have a 1/2" girdle, so either need to use the BRM sproket to gain some chain length, or find a custom chain.

I really don't think the BRM sprocket has anything to do with it. The pressure relief valve in the filter housing is pretty big, it should be able to handle the volume easily.

I have an oil pressure sensor mounted on the filter housing, sensing the gallery pressure going back into the block. I have never seen more than 85psi on the logs, even at 5400rpm.
Cold start is about 60psi. Hot idle is about 14psi.

Bummer Charlie. Let me know if you need anything from me.

Well.....

Mains and rod bearings are not too bad.
However piston #1 has badly scuffed its bore. The feed for oil squirter #1 is right next to the plug that failed, so I am guessing it lost pressure immediately the gallery plug moved, and before the oil light came on.
I suspect that the plug started leaking during the 2000-5000rpm logging run. The oil pump could likely outrun the leak volume until the pan was emptied, and only then did the oil light come on.

I am going to take it to my machinist and see if he thinks he can clean it up, I suspect not. If I am lucky it is mostly aluminum piston deposit on the wall, and minimal ring scratches.
I am already at 81.5mm bore, so cannot overbore again.

Pics :

Oh, and for FUB and others wondering how 260+bar PCP treats the rod bearings... this is after 4000 miles and a lot of WOT logging runs. Pretty nice.

Wow Charlie. I gasped when I saw that piston. Hope the cylinder is repairable. That really sucks.