As is the way in the UK when using any expert service, and paying UK expert prices, there are always problems that are mine and not theirs. To date, 4 of the 6 main core plugs have leaked. The three on the exhaust side, whilst a hassle, I have redone. The latest is the one at the back on the inlet side, no real prospect of doing without having the engine out again. Many years ago, I affected a ‘repair’ on another engine by draining coolant, drying off, and then sealing over with JB Weld which proved very effective.
On this occasion, I thought I’d chance it by use of a modern material. I don’t know if available elsewhere, but in the UK it is ‘Adiseal’ – an adhesive sealant, popular with builders, plumbers etc. A feature it is will seal & cure under water…
Hence, with shredded knuckles I cleaned the offending area until there was the vaguest evidence of leak, plastered over with adiseal, and to date (few weeks / few hundred miles) it has held – We shall see. If it fails I’ll then revert to bodge B (JB Weld) and drain coolant etc. If that fails then bodge C (glued in expanding core plug).
I had fairly good luck with those expandable rubber core plugs on Tweety: places that were just so hard to get to, I put those in and then I would just make sure to snug them once a year. They never leaked.
I havent done all that many core plugs, but when I did, noticed the casting holes had a buildup of iron oxide that had to be physically scraped away and sometimes you could see little pits of erosion in the iron block, but I got lucky, maybe cause I prepped each hole well enough, if the pits were bad, I guess you would have to fill them with 2 part epoxy and sand smooth
I bet they didnt pay enough attention to detail there, the back one is a sin
I suppose its one of those things with an engine rebuild maybe they try to cut corners on cleaning as I find it so time consuming, maybe pro ships just dip the block and say its done, but I would probably spend maybe 30 minutes on each core plug hole, remove, careful inspection, scraping and wire brush, nothing else will cut it with old engines
You would think a pro shop would just know they have to do it and allow time, but ~3 hours on core plugs might be $450…maybe the apprentice does them …who knows ?
I dont bash them in either, but pull them out with a slide hammer (unless it wont fit)…for the same reason, I dont want to compromise the core seat and lip
With regard to engine out, when my 3.8S got its comprehensive overhaul a few years ago I was amazed that it look less than 8 hours I think to get the engine out and on a rolling table of sorts. The shop rolled the subframe with wheels attached, out from under the car, removed the carbs, pulled the exhaust manifolds back against the inner fender, dropped the gearbox mount and then raised the body up and clear of the power train. It all looked so easy but I’m sure that even with this method it was still complex.
When I restored my MKII, I placed a small bead of JB Weld around the groove in each hole and then installed the core plugs. Another small bead around the plug edges after install. That was in 1989 and they haven’t leaked yet.
I used that stuff on the centre exhaust side on the my Mk2 because of your history. It’s just a standard style “centre deformed” type and no leaks over two summers.
