Anyone have any experience with a freeze plug under the valve cover popping? No other plugs are affected. question is pull the head or JB weld the plug inplace and carry on?
Cylinder Head internal freeze plug
- Thread starter webert1316
- Start date
Did you find the previous plug? Was it properly staked? Ordinarily a freeze-plug is slightly-larger than the hole, and it is domed.... When installed it is ”set” with a punch and mallet. An impact socket 2/3rds smaller than the diameter of the plug can be used in lieu of the proper punch. Permatex No. 1 is what is normally used, not JBWeld.... but I see nothing wrong with JBW.
Looking at the adjacent one I suspect the plug corroded on the coolant side until it did not have enough structure to keep secure.
Clean the hole. Buy a new plug, put an anaerobic sealant like Loctite 518 around the edge of the cup before forcing it into place.
I see the hard JB weld not dealing with the cast iron head and sheet metal cup's relative expansion and contraction in the long term.
The WSM may suggest another sealant. and should be checked as the preferred one to use.
If as I suspect the cups/plugs are corroding on the coolant side, all of them will be in about the same state and replacing them now might be prudent.
There are two different sizes as shown below. 12 of the smaller ones and 1 of the larger.
Dave
Clean the hole. Buy a new plug, put an anaerobic sealant like Loctite 518 around the edge of the cup before forcing it into place.
I see the hard JB weld not dealing with the cast iron head and sheet metal cup's relative expansion and contraction in the long term.
The WSM may suggest another sealant. and should be checked as the preferred one to use.
If as I suspect the cups/plugs are corroding on the coolant side, all of them will be in about the same state and replacing them now might be prudent.
There are two different sizes as shown below. 12 of the smaller ones and 1 of the larger.
Dave
I like the copper or brass freeze plugs, because you never have to deal with them rusting out ever again. I would also do a block / radiator cleaning and flush, to remove the internal rust in the block and possibly the radiator core.
Thanks for the replies. The plug that popped out is in good condition. The plug next to it is pushed up ready to come out when the pressure comes back. I'll attach pictures next time I'm at the tractor. I'm a hundred miles away right now. Since it came out in one piece I'm wondering if there might be a head gasket leak that pressurized the water jacket. I would think that the radiator cap would release the pressure before the freeze plug popped, but IDK.
Thanks GeoHorn, the plug was lying on the head in one piece, couldn't tell if it was properly staked. The plug next to it is starting to come out as well, thinking a pressure leak from the cylinders?
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rbargeron
Well-known member
Lifetime Member
Equipment
L5450, L48, L3250, L345 never enough attachments
This looks like weak (or no) antifreeze, and freezing water started pushing them out. The good news is they did what they're supposed to do, saving the engine. Keep looking - there may be more that moved.
It doesn't take a lot of force to keep them in place. When running at normal temp the radiator cap and/or hoses will leak around 20 psi. But ice expanding without antifreeze can break iron.
It doesn't take a lot of force to keep them in place. When running at normal temp the radiator cap and/or hoses will leak around 20 psi. But ice expanding without antifreeze can break iron.
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I remembered reading that what is commonly called a freeze plug, is actually a core plug. The reason this caught my attention in the past, is because I did some sand casting with aluminum.
Just did a search, to see what I could find. No idea if this is accurate or not, but I think it may be:
The term freeze or frost plug is slang; the correct name of the press-in plugs is actually 'core plug'. It is mistakenly thought that the purpose of these plugs is to be pushed out and save the block from cracking if the engine has water in it and it happens to freeze. This is nothing more than an urban legend.
The purpose of the plugs is to fill the holes that were made during the casting process, so the foundry could remove the 'core' sand from the coolant passages. Saving the block from cracking in case of a freeze was never the manufacturer's intent for these plugs.
The purpose of the plugs is to fill the holes that were made during the casting process, so the foundry could remove the 'core' sand from the coolant passages. Saving the block from cracking in case of a freeze was never the manufacturer's intent for these plugs.
rbargeron
Well-known member
Lifetime Member
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L5450, L48, L3250, L345 never enough attachments
Yes being movable may not be their intended purpose, but a lot of engine castings have benefitted from having them. They work if the freezing event isn't severe.
kubotafreak
Well-known member
Equipment
GRAND l6060, L3560, B6100, gr2100, tg 1860, g1800, g1900, g2160
If they are stainless steel just reuse them. Diesels commonly have stainless steel. If they are zinc coated replace. I usually put sleeve locktight on them. Tap them in just a mil below the deck. If one pushed out, guaranteed others have shifted. There are some behind the timing cover too.
The parts catalogs at Toyota (where I worked as a young mechanic back in the early ‘70s) called them Welch-plugs. I’ve also heard them called “boss plugs” in British terminology.
I remembered reading the term Welch Plug. Took another look and this turned up:
The Welch plug is a type of core plug that is made from a thin disc of metal. The Welch plug is dome-shaped and inserted into the casting hole with the convex side facing outwards.[5] When installed by striking the Welch plug with a hammer, the dome collapses slightly, expanding it laterally to seal the hole. This differs from other dish-shaped core plug designs, which form a seal when their tapered sides are pressed into the casting hole.[6]
The Welch plug was originally designed in the 1900s at the Welch Motor Car Company in the United States. Prior to the invention of the Welch plug, the core holes were sealed using pipe plugs. During the testing of a car, one of the pipe plugs backed out. In order to get back on the road, one of the Welch brothers installed a press-fit quarter or half dollar coin into the hole using a hammer. The design of the Welch plug was refined based on this principle of a press-fit metallic disc.[
Just find this interesting...sure seems like while the plugs may help when there is a freeze in the engine, that was not their primary reason for existing.
whitetiger
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Equipment
Kubota tech..BX2370, RCK60, B7100HST, RTV900 w plow, Ford 1100 FWA
By the time your coolant is cold enough to expand and push out a soft plug, is not going to drain out of the block, it's frozen, aka ICE.
If it FROZE... it wasn’t the “right stuff” anyway and needs to come out.
The questions are, as I see them, are “WHY did the plug come out?” and “What do I do about it?”.
It’s possible the plug and/or the head released due to improper installation, or loss of material due to corrosion, or “other”... but in every case it obviously needs to be repaired and the others should be inspected to see if the same problem also exists.
Thanks Guys, all good stuff.
Right now the plan is to pull the head to inspect cylinders and head gasket. Depending on what the head looks like when it's off, either take it to a machine shop for rebuild and have plug replacement performed OR if it looks worth the risk new head gasket and plugs with proper sealant. Will definitely go over the rest of the plugs to check for movement. The coolant that was left in the radiator looked about the same as the 50/50 mix I added after draining the old stuff. That's not to say there wasn't an oops moment with the previous owner who then put the correct coolant in afterwards
Right now the plan is to pull the head to inspect cylinders and head gasket. Depending on what the head looks like when it's off, either take it to a machine shop for rebuild and have plug replacement performed OR if it looks worth the risk new head gasket and plugs with proper sealant. Will definitely go over the rest of the plugs to check for movement. The coolant that was left in the radiator looked about the same as the 50/50 mix I added after draining the old stuff. That's not to say there wasn't an oops moment with the previous owner who then put the correct coolant in afterwards
UPDATE. Got back out there and pulled the head. The head gasket looked ok except for the water passage holes being different sizes. In the picture you can see the holes for cylinders 1 and 2 are a lot smaller than the holes for 3 and 4. Cleaning up the head and deciding whether or not to take it to the machine shop to get checked out. It was running, everything looks okay wondering if I should just reassemble. If I do take it to a shop, do I need to pull the injectors and glow plugs? Guess I'm asking how far down I need to strip it before taking it in. Is there a special tool to pull the injectors? After you remove the hold on bolt, do they pull straight out? TIA
