Coolant Leak

I have a 1964 MGB, stock engine except the alternator and manual plumbing fixture for the heater control valve. Head rebuilt last winter and installed by a reputable MG expert mechanic. This winter, I have developed a small coolant leak. I drive the car once a week or it may sit for as long as three weeks. I have a plastic drip tray on the floor.

Four or five days after I drive it, a small puddle of coolant, perhaps a thimble full or two, will appear on the floor of the garage in the tray. It appears to be coming off the back edge of the cross member just about dead center. I check every day. The drip does not occur until it has been sitting several days. I checked all hoses and hose connections. The heater valve is dry. Radiator seems OK. Nothing obvious with the water pump area or head gasket, although the water pump seems to be most likley culprit given the location.

What is y'all's advice on where to check next? Thank you.

Jim

If the source of the leak is not visually apparent then my advice would be to clean down the engine and all hoses etc, take it for your normal drive and when it has cooled down shake some talcom powder around. The leak will then become visible thru the talcom powder getting damp.

Russ

Maybe there is a slow leak in the radiator. It might be filling up the top of the radiator base where there is a little lip. when it fill up after a few days, it spills over that lip and leaks down onto the crossmember.

I'd double check to see that the hoses are in good shape and FIRMLY attached to the inlet and outlet necks on the radiator and waterpump. If there is any corrosion on the metal necks it can interfere with the seal of the hoses.

Just my guesses

You can purchase a leak-detection kit that includes a "black-light" (remember those?) that will light-up the coolant for easy tracing. Apparently an LED light will work as well.

I found a pesky leak on my V8's water pump using this kit as well as an oil leak using the dye that comes with the kit.

The company name is "UltraLite". I purchased the kit at our local Canadian Tire store but I'm sure it's out there elsewhere.

Run a finger under the neck oj the water pump behind the pully. If it at all even damp the seal fo the shaft is starting to leak. There's what's called a weep hole at the bottom of the neck.

Sounds like above mention weep hole. Also check to see that water pump bolts have not loosened.

I think an old fashioned pressure test would work better than the dye-powder test. pump it up to 15 psi then start feeling with your fingers under the water pump, at hose ends, etc.

Thanks folks. I'm starting to go through to sort it out....easy things first.

Is it worth it to just change just the seal in the water pump if that turns out to be the problem, and would just go ahead and replace the pump while you have it apart....given that the seal is basically $12 and the entire pump is basically $80 (at Moss full retail anyway).

Gordon at the B-Hive has your water pump for $62.21. And he's a GREAT guy to deal with - even has a British accent!

Here's the link:

http://bhive.tierranet.com/109MGBwaterpumps.html

Gordon has cast iron pumps (only ones to use) and it will get to you overnight, being so close.

As a bonus, your engine won't get diaper rash.

If your leak turns out to be the water pump, replace the whole pump and not jsut the seal. Usually when a seal goes bad, the bearings are not far behind.