Gary,
I have a 3GM30F and Section 4.2 of the GM Series Service Manual says the fresh water enters the cooling tube cover through a hole drilled at one end of the cooling tube, circulates around the ~24 raw water tubes inside the cooling tube, then exits through a hole at the other end of the cooling tube cover. My guess would be if you have “additional” holes in the cover in the form of the perforations you noted [beyond the two that are supposed to be in the cover] it would not affect the cooling and would be OK. It appears the “hot” fresh water coolant from the engine block is just pumped into the heat exchanger body and flows through and around the cooling tube cover and its raw water tubes and then is pumped out the bottom of the heat exchanger body. It looks like the whole cooling tube assembly is basically bathed in the fresh water coolant, so there should not be an effect on cooling efficiency. I have a mechanic working on my engine now [determined to be blown head gasket] and will ask him for an opinion. Brian From: CnC-List [mailto:[email protected]] On Behalf Of Gary Russell via CnC-List Sent: Thursday, August 13, 2015 4:16 PM To: C&C List <[email protected]> Cc: Gary Russell <[email protected]> Subject: Stus-List Yanmar Heat Exchanger Well, I bought a C&C 37+ a few weeks ago and have been having nothing but trouble. It started with a fuel injector seal failure that allowed combustion gases to escape into the cabin. Below the injectors are pre-combustion chamber that where frozen in place requiring the cylinder head to be removed. While the head was out, I decided to do a valve job. And since the heat exchanger had to be removed, I decided to have it cleaned out at a radiator shop. There is an aluminum sleeve around the cooling tubes in the heat exchanger that had perforated. My understanding is that raw water circulates through the tubes and fresh water surrounds them. It seems there is fresh water on both the inside and outside of the aluminum tube, so I'm not sure if the perforations are a problem. The radiator shop guy wasn't sure either. It wouldn't matter, except the heat exchanger is no longer available from Yanmar and the cooling tube assembly is $1K, and can only be replace if (big if) I can get the frozen one out. What happens if I ignore the problem? The radiator guy pressure tested the assembly and it held pressure. Any ideas? I'm really desperate! Gary '90 C&C 37+ High Maintenance East Greenwich, RI, USA ~~~~~~~_/)~~~~~~
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