"The motor I just bought rebuilt from a veteran mechanic (72 yrs old) that has been working on them for 20yrs he says and has had an answer for avery question I have ever asked. So my problem is I keep blowing out freeze plugs one at a time as I start to throttle up and get up on plain. The motor will sit and idle for as long as 15-20 minutes and idle in gear with out blowing a freeze plug for as long as I can stand waiting probably ... 10 minutes. Then I throttle up and within 2-3 minutes a freeze plug will blow. I have replaced 1 only, factory. I replaced it with an aftermarket and that one held on the second run another factory one blew. First it was the one behind the oil pressure gauge on the left side. The next one to blow was the third one on the same side.
I need some ideas of what may be causing it to happen. We have alredy checked the flow in the heat exchanger and while it is sitting and idleing the water is circulating through the motor as needed as far as I can tell.
What am I missing?
My mechanic is building me another and wants to swap it out, but it runs so sweet at idle, smoothe as can be. There is a reason it is happening.
The hoses are lined with wire and not callapsing, it has a new raw water pump and circulating pump. There are no leaks anywhere. Temp. stays stable at idle for up to 15-20minutes of sitting still out of the water.
Any new ideas will help thank you."