Hairline crack in manifold

[jfridlington]

I have a 4 inch hairline crack in the maniflod right beneath where the firing order is stamped. The crack is very small, nearly undetectable - it looks almost like a paint chip is coming off. When the engine is running at low RPM nothing appears to be wrong however at higher RPM small amounts of water seep out the crack. All that said I have 3 questions.



1) What is the best corrective action to take. Should I start planning on replacing the entier manifold or is there another alternative?

2) How critical is it to make the repair? Can it make it until the end of the sailing season? (I sail on an inland lake approx 1 mile wide and 7 miles).

3) I want to perform the muratic acid flush described on this site as part of a thermostat replacement and water pump upgrade project. What are the thoughts of performing the acid flush with the crack there?


Thanks in advance for any advice.

[rgoff]

There something called "JB Weld" that I've heard people rave about. It's like an epoxy glue.

http://jbweld.net/index.php

[Don Moyer]

Jfridlington,

Unless you're planning to acid flush due to an actual overheating condition, I'd delay that procedure and take care of the crack in the manifold. Clean the surface around the crack down to the bare metal, and then apply a layer of fiberglass material from the small fiberglass repair kit from West Marine (West Marine Model number 399883). Mix the glass powder contained in the kit with the epoxy until the mixture resembles thin mayonnaise. If you clean the metal well, such a repair should at least get you through the current season.

Don