Plastic thermostats? New to me. We do about $400k a year with Stant but most marine thermostats are Robertshaw as an OEM. I could see plastic as a pressure relief valve but could not imagine a nylon filled glass composite being able to withstand that kind of loading without blowing the top off of the thermostat with a minimum of 50,000 cycles needed for the standard stat made from 409 stainless steel or 85/15 brass, amazing. We need an OMC guy to walk us through the upgrade. Which engine do you have 60 degree lopper or 90 degree cross flow? Futch, you seen this?
Those are called vernatherms. same as tstats with poppet included. OMC had a problem with the original seats for those with fins that sat into the grommet. You need to replace grommet, vernatherms, diaphram and if I remember correctly the covers also. They had a kit for this at one time. I will try to look it up today and see if I can find the info. Been years since I have seen one of the original ones. The update took place in 92 or so. The issue was that corrosion would build up behind the grommet and lock the vernatherm down causing an overheat at WOT. With the SLOW system they had at the time the RPMs would drop from WOT to approx 2200 rpms immediately. Depending on the boat, the captain would go thru the windscreen and the passengers would go swimming LOL.
Farley, if Ford can make intake manifolds for 4.6 V-8s that live in the valley of heat, out of plastic...just sayin...
