Maristar Overheating

[chris hodge]

I have a 98 Maristar 225 with LT1. I changed the impeller and now it is over heating. Was not over heating before. I made sure the impeller blades were going the correct direction. Any advise?

[Jerseydave]

Just some guesses:

gasket in place on the cover?
all hose clamps tight? (if the pump sucks air it will not pull enough water to keep engine cool)
semi-clogged oil cooler? (did the old impeller have any vanes missing that might be stuck in the oil cooler?)

[chris hodge]

I pulled hoses around impeller and everyhting clear and well sealed. old impeller had all the viens still there. I pulled both thermostats and I think they look pretty old. I heated up water and they both opened. Not sure if the temp was right. I am going to get new ones. I think I might flush out the system. not sure if that is hard to do. I try to do preventative maintenance and it causes this heat issue. Not sure if I shed any light on the problem. Thank you for your reply.

I will check the oil cooler.

[Ski-me]

Check both your thermostats and I'd replace them as a precaution. If you have the same LT1 as me (94), your top one is a 160 stat with a small hole drilled in the top, and another 142 stat down by the waterpump.

I also replaced my temp sending unit that's on the block. pretty cheap item.

Also be sure there aren't any small impellar pieces floating around....

[Barefooter92]

I had overheat issues all last week. Changed the impeller, t-stat, checked everything only to find weeds impacted on my transcooler.

I used a toy water canon to back flush the transcooler into the bilge. I removed two hand fulls of weeds.

Works like a champ now.

[chris hodge]

Thanks for the information. I pulled a hose today and had the impeller suck water out of the bucket. That worked. going to change the thermostats and see if that helps. Next will be the oil cooler.

Thanks for the reply.