New owner with ?'s re: w/h and overheating

[Tom Ehmke]

Just brought her home this summer and put 800+ miles under her bow. I have had a couple of problems and have already checked the archives but am unable to find any answers or suggestions about the random overheating problem. I think I have it fixed now, but I want to know if this is symptomatic on a Cat 30 with a w/h.So here is the problem. Occasionally the Temp. Gauge would spike all the way up to 240 degrees without any unusual strain on the engine. At other times it would do it just when I needed the engine in rough weather. I checked the thermostat and it is ok. I have since ordered a spare. One morning my crew and I decided to do some trouble-shooting to analyze the problem and fix it (hopefully). I read the section in the owners manual (yes, the previous owner had left it for me, bless his heart!) about problems with air pockets in the coolant line if a water heater is on board. We took a good look around in the lazarette and discovered that there was a coolant overflow tank in the lazarette for the water heater located there and another coolant tank located behind the port settee in the cabin area. What we learned is that the coolant poured into the tank in the lazarette was siphoning into the tank behind the settee because it was located lower than the one in the lazarette. After all the coolant was siphoned out of the higher tank the coolant would flow through the line to the lower tank and overflow into the bilge. Then it would suck air into the system. It cost me almost a full gallon of coolant to figure that out. When I brought the boat there was no coolant in the overflow tank for the water heater and the previous owner didn't mention anything about it to me during the sea trial and walk-through of the boat systems. Now the overheating problem is fixed, but I want to know what to do with the overflow tanks. Which one should I disconnect? Or does it matter? Has anyone else dealt with this problem? I read that there should be a bleeder valve at or near the water heater. The only one that I am aware of is the one at the top of the thermostat housing.Any advice would be appreciated. Right now I have a vise grips clamping the line off at the overflow tank by the water heater to stop the coolant from siphoning, but it is still being drawn slowly past my "clamp".Thanks and boy do I love this boat!!!Tom Ehmke

 

[Calif. Ted]

I've attached JPEG of exploded diagram

for Seaward WH circa 1993. Shows drain valve (#8) and pressure relief valve, I don't understand overflow tank at the waterheater, hope this may assist.

 

[Tom Ehmke]

Ted, what I am looking for is a bleeder

I located the pressure relief valve and drain cock earlier. What I am looking for is a bleeder valve which will remove air from the line at the water heater end of the coolant circuit. If there is nothing like that on the water heater, I am trying to find out what to use to bleed the line when I disconnect the overflow tank in the lazarette. I may not need anything there if the bleeder valve at the thermostat housing will take care of the problem. The boat is new to me and I am hoping to get answers from other 30 owners which work and are simple to do. (Yeah, right... on a sailboat???)Tom

 

[Calif. Ted]

My boat is a 270 so may be a little different

but I'll try to look today and let you know when I get back Friday. Catalina doesn't vary stuff any more than they have to, so the boats have much in common. I haven't had a problem so haven't done more than just glance at it. I'm not sure if the drain valve is for coolant side (in which case it will bleed air) or to drain the tank, I should be able to check pretty easy. What is the overflow in laz plumbed from ? Maybe that's the bleeder and PO put the tank in to catch coolant when bleeding and now valve is leaking ?

 

[Calif. Ted]

Tom, check the front bulkhead,

of the port lazzarette, on the coolant line is a copper pipe tee with the bleed valve, may not be in exactly same place on your boat but it must be near the WH and probably standard pravtice for Catalina to do it this way.