Core plug adhesive ?

[waynes world]

I part rebuilt a VP AQ130 last year and good job i ran it again a while ago on blocks, its not fitted yet. One one of the core plugs was loosing water and then it came out easy. Core plug is good but te aperture is rough so ill be cleaning back.

Now wat is the best core plug adhesive to use on marine engines. Or is standard car engine core plug adhesive good enough.

Cheers

 

[rotrax]

I have never used adhesive on a core plug. AFAIK there ate two types, one a thin convex type with a tapered seat around the edge, the other a pressed one with a parallel lip, sometimes a 1/4 of an inch.

Both were an interference fit and the first was placed in the core hole and then hit in the centre with a blunt punch. This caused the edge to expand and the taper to seat tightly in the block. The second type got larger towards the outer edge of the lip. Tapping/punching it in with a sized punch tool sealed the core hole in the block.

If there are more modern ones, they are outside my experience.

 

[Refueler]

Never needed adhesive to install Core Plugs ... they should be as Rotrax says - a press interference fit.... needing a rod of similar diameter as the inside of the plug and a small hammer to 'tap' it home ...
I use a wooden dowel as the drift.

If you can press in easily - then its wrong size. I know with my Perkins 4-107 - I have to make sure my plugs are Imperial size as the Metric are very close in size but not tight enough fit ...

 

[waynes world]

Sorry adhesive was wrong word, sealant. but always think of it as adhesive sealant for some daft reason.

It is the correct size plug but not very tight. but then the i fitted new ones in the head tat were not as tight as expected. this i did not fit. Just ran the engine up and it was leaking were a sit want last year.

 

[William_H]

It does look like the mating surface of the hole has been roughened up with corrosion from long term leak. Clean it up and check for tightness of fit of core plug. If you can not get a decent fit then I can only suggest a high temperature epoxy to seal it. ol'will

 

[Poignard]

Last time I fitted a core plug I got some sealant from a car accessory shop.

Hermetite?

 

[Daydream believer]

Mate of mine had a leak on a core plug on a 20HP Beta when on holiday last year. It was in a place he could not get to to drive it in tighter. His solution was to smother it with "Sticks Like" & another plug over the top to hold the mastic in place whilst it set. He forgot about it until this year & it worked for over 50 engine hours before he got round to changing it. Even then he said that to his amazement it looked as though it was perfectly OK

 

[waynes world]

Mate of mine had a leak on a core plug on a 20HP Beta when on holiday last year. It was in a place he could not get to to drive it in tighter. His solution was to smother it with "Sticks Like" & another plug over the top to hold the mastic in place whilst it set. He forgot about it until this year & it worked for over 50 engine hours before he got round to changing it. Even then he said that to his amazement it looked as though it was perfectly OK

Going to get some J B weld or similar. Just trying to find it locally.

 

[burgundyben]

Looks ike a crack in the block.

 

[waynes world]

Looks ike a crack in the block.

yes looked like it in that pic but its good, took another pic to double check.

Got some JB Weld High Heat Epoxy on its way.

 

[Refueler]

yes looked like it in that pic but its good, took another pic to double check.

Got some JB Weld High Heat Epoxy on its way.

Just mentioning - the Core Plug serves two purposes :

Primarily it is actually a plug to seal the casting hole ... from when block is cast.

Secondary it is a protective item should water freeze in the block that should pop out ... not very effective actually ... blocks still crack water channels etc.

I have temp repaired corroded plugs by use of Plastic Metal .... but to be sure that PM does not get into block when pressing it into the plug - I fit a disc of material ... an old foam ceiling tile ... cut out from plastic carton ... anything that can be pressed into plug to provide a 'wall' to then put PM up to and seal the corroded plug.
Done well - it can last years !! Guess how I know >>

 

[fisherman]

I had an almost invisible hairline crack that allowed the plug to drop out as soon as the temp went up, about a mile out. I had some trouble putting it back in but it popped out very easily when hot. Spectacular rise in engine temp and instant alarm.
I though to fix it with drilled and tapped holes and a plate with gasket, but I had mech insurance, so new exchange engine.

 

[PeterWright]

In my experience, core plugs are designed as a single use device being convex in form. Once in place, a couple of firm taps with a hammer, with or without a drift, flatten the convex form a little causing its diameter to increase and sealing it in place with no need for any form of adhesive or sealant.. It's a long time since I bought one but they were never so expensive that it was worth trying to save money by not replacing them if you had one out. I seem to recall that there was an issue with both metric and imperial sizes which could not be successfully confused.

 

[Plum]

Just mentioning - the Core Plug serves two purposes :

Primarily it is actually a plug to seal the casting hole ... from when block is cast.

Secondary it is a protective item should water freeze in the block that should pop out ... not very effective actually ... blocks still crack water channels etc.

>>

As you say, not effective. It is a myth that they also serve as a protection against frost. Yes, they pop out if the water freezes but the chances are that the block or head will crack anyway. Their sole design purpose is to block the core holes in the casting.

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