Welch Plug Hole Badly Corroded

[aussie54]

Hi All. I am in the process of replacing the head gasket and found that one of my welch plug holes is badly corroded. In fact, the welch plug appears to have merged with the hole. I cleaned off some of the corrosion but It shows me that there is no longer an actual round hole in the block. Has anyone had this problem and if so how was it fixed? I have atttached some pics...... Your help would be appreciated muchly.....cheers.

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[Robo]

Gee that looks nasty, worse than a dirty nappy lol!

Whats the approx size of the hole you think?, this may help with ideas from our mates here.
really think you need to start looking at all the plugs given the state of that one and the muck around it.
the block looks like it needs some serious flushing, even your rad and the interior heater core.

looks like ya have nothing to loose but to flush/clean block/around the hole lots, to get a better look at the situation.
could get lucky and only be the face, not side of plug corroded.
all fingers crossed.

[the evil twin]

Eeeeyuk, That is seriously horrible eh, ...
Do they still do acid dips of blocks to clean out the galleries or can they not do it due to all the alloy these days?

[aussie54]

Gee that looks nasty, worse than a dirty nappy lol!

Whats the approx size of the hole you think?, this may help with ideas from our mates here.
really think you need to start looking at all the plugs given the state of that one and the muck around it.
the block looks like it needs some serious flushing, even your rad and the interior heater core.

looks like ya have nothing to loose but to flush/clean block/around the hole lots, to get a better look at the situation.
could get lucky and only be the face, not side of plug corroded.
all fingers crossed.

It takes a 18mm plug. It is the exhuast side of the engine. Yes it will need a good cleanout. I used a screw driver to scrap away the corroded bits and what is left feels solid. Maybe I can drill it clean and then maybe try and plug it.

[Cuppa]

Been using plain water as a coolant?

[paulyg]

You may be able to use JB Weld on it and then grind it back.

[dom14]

Been using plain water as a coolant?

That must be the case.

Cheapest solution might be to weld a permanent plug?!!!

Or cut it to next plug size. A hole cutter can do it, with a 90 degree attachment to the drill.

Either way, use JB weld or similar compound around the seat.

[aussie54]

Thanks for your replies. Yes for a long time it only had water in it as the head gasket was leaking water out and it was being topped up regular with just water. Did not have a oportunity to fix it. My Bad in many ways. I thought about using JB weld, but not sure how long it would hold. I do have a 90 Degree drill attachment and after I remove the exhuast pipe I will have a little more room.
May give it a go this weekend. Thanks for all your replys.

[dom14]

Thanks for your replies. Yes for a long time it only had water in it as the head gasket was leaking water out and it was being topped up regular with just water. Did not have a oportunity to fix it. My Bad in many ways. I thought about using JB weld, but not sure how long it would hold. I do have a 90 Degree drill attachment and after I remove the exhuast pipe I will have a little more room.
May give it a go this weekend. Thanks for all your replys.

Use anti corrosion additive with few bottles of distilled water. All of that costs less than $15 at Super Cheap Auto. Anti freeze bit more, but nowhere as critical as anti corrosion in Australian climate. Never use water for more than few days. I use plain water when I try to flush the coolant system by running it through few plain water change cycles. Use the water drain plug at the bottom of the block to get rid of all the plain water.

[the evil twin]

Thanks for your replies. Yes for a long time it only had water in it as the head gasket was leaking water out and it was being topped up regular with just water. Did not have a oportunity to fix it. My Bad in many ways. I thought about using JB weld, but not sure how long it would hold. I do have a 90 Degree drill attachment and after I remove the exhuast pipe I will have a little more room.
May give it a go this weekend. Thanks for all your replys.

If you are planning on keeping the car for a while I don't think just fixing that plug is enough.
Hate to call it a 'tip of the iceberg' problem but I would be very concerned the corrosion won't be limited to just that plug.

What, if anything, did you notice when you had the head off to fix the gasket?

[aussie54]

Yes, will be keeping her and the head gasket was bad. She will be getting the proper coolant this time. There will be corrosion in other places like the heater core and radiator but I hope to clean those up.
An Update....After I cleaned up the welch plug hole, I found that there was part of the original mild steel welch plug there. Just the ring part. I think after I do a really detailed clean it will take the new one oK, with sealant of course. See the pics. Check out the comparsion of the old and new plugs.. Mild Steel and Brass.
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[the evil twin]

Good result, dude

Old school days we replaced all Welch Plugs if one was corroded, dunno if that is still the go.
Not trying to teach you to suck eggs but I'd be giving that block the mother of all flushes after you fix the sucker

[dom14]

Good result, dude

Old school days we replaced all Welch Plugs if one was corroded, dunno if that is still the go.
Not trying to teach you to suck eggs but I'd be giving that block the mother of all flushes after you fix the sucker

Absolutely!

I think it's a good move to replace all of them if time and space permits it. You would have to pull out both inlet and exhaust manifold to do that, which is the reason I didn't go for it.
I had a perfect opportunity to do it in my case when I had pull the inlet manifold out to do another job few weeks back, but I blew the opportunity by getting slack & wanting to get the
vehicle running straightaway.

I would attach a water hose and air hose to the top end of the coolant line(cylinder head) and flush the crap out while the welch plug hole is still open.
I'm about to do the same on mine, 'cos the welch plug I did over a month ago started dripping(I didn't use and sealant). Even though the dripping stopped(stopped by left over rust blocking it I reckon), I'm about to do it all over again. This time with Permatex aviation liquid sealant, epoxy or Loctite red thread sealant. I haven't made up my mind which sealant to use.
Mine had a bit of rust inside regardless of using distill water & anti-freeze. I reckon it was anti-freeze, but probably didn't have much anti rust action in that coolant. This time, I won't bother too much about anti freeze action but I'm paying lot of attention to get a good anti rust coolant concentrate.

[dom14]

Yes, will be keeping her and the head gasket was bad. She will be getting the proper coolant this time. There will be corrosion in other places like the heater core and radiator but I hope to clean those up.
An Update....After I cleaned up the welch plug hole, I found that there was part of the original mild steel welch plug there. Just the ring part. I think after I do a really detailed clean it will take the new one oK, with sealant of course. See the pics. Check out the comparsion of the old and new plugs.. Mild Steel and Brass.
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So, it's not that bad. But, make sure to use a good sealant like Permatex aviation sealant or something as good as that.
I'm about do mine as well. I haven't made up my mind about which sealant to use yet. I have Loctite red, Permatex aviation sealant and epoxy all ready.
I think I go with Permatex aviation sealant. Burson auto guy suggested it's the best for the welch plugs.
Do a good flush first with combined air and water combined, then put it through couple of cycles of plain water to get more grime out.
It's possible to do that if you have access to the water drain plug at the bottom of the block. It's usually on the exhaust side of the block.

[aussie54]

Hey Guys... Thank you for all the good advice. Yep,. after I get the head back on, I will do a complete cleanout and flush. Not much point doing it with the head off as there are too many open holes at the top of the exposed engine block and there would be no pressure to help it all come out. Some of the plugs had been replace before with brass so they should last years mores...one hopes.... For those interested... here are some pics I took.
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[aussie54]

Sorry guys, forgot to mention my patrol is a 1991 GQ LWB, TB42 Carbie Engine, on LPG. 370K Kms....

[aussie54]

Success! Finally did the job. Here is a before and after pic.
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[dom14]

Success! Finally did the job. Here is a before and after pic.
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What did you use as a sealant?

[aussie54]

LOCTITE AUTOMOTIVE NO.3 NON-HARDENING SEALANT AVIATION GASKET SEALANT.
Have been using it for years and years and never let me down.

[dom14]

LOCTITE AUTOMOTIVE NO.3 NON-HARDENING SEALANT AVIATION GASKET SEALANT.
Have been using it for years and years and never let me down.

I used the same stuff, but Permatex brand. I also think Loctite red thread sealant is a good option as well.
If I have to do another one, I'll use loctite red, but need to make sure to leave it for 24 hours before filling up the coolant system.