MGB101 Question!!

Gentlemen: I suspect that last year when a "professional" mechanic replaces my head gasket and head, he didn't get enough coolant into the system. This is a 77 and you know how they don't have a radiator cap! I seem to remember that there is a sure fire method of preventing air bubbles when pouring in the juice, which involves lifting the front end of the car and maybe even drilling a small hole in the rim of the thermostat? Am I dreaming this? When I mentioned this to the guy he just stared at his shoes for a few minutes. Anyway, I would like to drain it out and refill as to reduce my anxiety, just on this particular issue, of course!!! Any hints on this?

Well I cant say abt a 77B (mines a 72) but it was suggested I drill a 1/8' hole in my B4000's thermostat to reduce the risk of the intermittant overheating problem we have with it. Yes it is supposed to help get rid of any trapped air - or so Im told.

When I had a 77, living in Phoenix, I would open the thermostat housing (just take that brass nut off), and make sure the front of the car wasn't on a downward slope or anything. Front needs to be level, to slightly high.

Then, with the car running, I would add fluid as needed. Never had a problem.

and turn the heater on to fill the core

You don't need to do any drilling of anything. Just get a plastic funnel that has a neck that will fit in the fill hole. It will be tappered. Turn it as if it was treaded and it will kind of screw into the hole. Now take the cap off the overflow tank. Pour coolant till the overflow tank fills. Next put the cap back on the overflow tank fill the funnel and sqeeze the bottom radiator hose till no more air bubbles come out. Once you have gotten all the air bubbles out suck the remaining coolant out of the funnel. Replace the plug, and you are done.

What Tom just described was a professional's method of 'burping' a late car with pressurized system....i do the same thing by removing the bolt in the top of the thermostat housing & pouring water in it wehile engine is running & a buddy squeezes the bottom radiator hose.....Tom's way seems more efficient...ya gotta 'burp' late systems to get the air bubble out!

Tony, thanks! As your doing this squeezing with the top plug out, would you leave the radiator expansion tank cap off too, or keep it locked?

Dan

Tom, thanks. At some point today, I pulled that thermostat out and drilled the little hole in it, just like you didn't suggest! Guess it couldn't hurt. I really think I've got a bubble in there so I'll try your burping method, maybe without the appropriate funnel. The car runs fine except when she sits for a while, I can tell the temp goes up a little high, like around 1 o'clock on the dial and the fans come on and don't turn off. You have to get the car in motion for a good 10 minutes to get it back down to normal. I never had this happen until the head gasket was replaced so I'm suspicious. It just seems like not enough coolant. Dan

It want work properly without the funnel. Filling the funnel puts the fill level up even with the top of the heater box. Plus if you don't have the funnel all you will do is sqeez air out and suck it right back in. Get the funnel. It might cost you a buck and it want be the last time you need it.

I just (at 10:15DST) FOUND a perfect funnel in the garage and have inserted it into the threaded socket. Great advice. This looks like it's going to work. Thanks!!!!!

I can see why Tom uses funnel...it does keep everything overfilled....no, close off the expansion tak so it doesn't draw air either

You will be chasing your tail without it.

Done! Thanks, guys. At least I got another 10 oz into it. This eliminates another variable! We'll get her on the road tomorrow and see what happens. This could be a case of "over concern" since it's not actually overheating. We'll see what happens in the everlasting Dunkin drive through in the morning.
Dan