I can’t see it, but the leak is there…

November 1, 2017 | By Staff


I’ve received your magazine for years. Great information. Problem is I cannot always find that information later. I have a 1961 Bentley S2 (seen below) with a “small” coolant leak somewhere. It’s not big enough to see, but I can smell the antifreeze. If I remember correctly, you recommended a cooling system sealant in a previous article. Could you please send me the name of the product and a possible source for it?

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Auto Restorer contributor John Armstrong was quite pleased with the results he obtained with these products, and he wrote the April and July 2014 articles to which you refer. I have not used them myself, but I trust Armstrong’s assessment completely and will certainly give Blue Devil a try should the need arise. The company makes an array of products for stopping leaks and sealing engines, and has been in business for many years.

You probably need their radiator and block sealer (part number 38386), which comes in 32-ounce bottles and sells for $64.99. Their products are sold by dealers around the country, and Blue Devil can tell you where to go to get them,or you can order directly from their website at: www.gobdb.com or by mail from:

Blue Devil Products 854 Lowcountry Boulevard. Suite 101 Mt. Pleasant, SC 29464

The stop leak may well solve your problem, but I would recommend trying to locate the source of this leak before it gets worse. You usually can’t find small leaks with the engine shut off and cold. To find a small leak, first start your engine and then with it thoroughly warmed up and running and the heater on, examine all the joints and hose connections for the cooling system; especially for your heater core.

Coolant is toxic, so you don’t want it wafting through the passenger compartment of your car. If you smell it while driving I highly recommend that you give your car’s heater core a careful once-over and fix or if necessary, replace it as soon as possible. In fact, if you have to drive anywhere, put the windows down, and if the leak gets worse, stop immediately and have the car repaired.

Leak stopping products are fine, but it would be prudent to determine where the coolant is coming from in any case. After your engine is thoroughly warmed, get a flashlight and a rag and feel carefully around each connection. Sometimes a joint merely sweats coolant when hot and doesn’t leak at all when cold.