I have a 1985 H31, which overheated (2GM) twice while bringing her home from winter storage. Was motoring in strong headwinds, about an hour out when she first overheated, shut her down awhile and she was OK...then she overheaded again while entering the marina. Since then, ran her 15 minutes in the marina, with no overheating. Coolant is fine and shows no bubbling. Any ideas?
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bob
carbon build up in exhaust elbow or possibly
the strainer in your engine raw water intake needs to be cleaned...unless you are very handy, carbon build up in the exhaust elbow will require a diesel mechanic..
the strainer in your engine raw water intake needs to be cleaned...unless you are very handy, carbon build up in the exhaust elbow will require a diesel mechanic..
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Dave Winiker
Overheating
Same thing happened to us last year. Suggest you check the raw water pump on the front of the engine. Found the impeller bushing had come loose. Piece of cake to replace the impeller.
Same thing happened to us last year. Suggest you check the raw water pump on the front of the engine. Found the impeller bushing had come loose. Piece of cake to replace the impeller.
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Les Andersen
Hot
Gil, I would bet on something in the cooling intake line over the exhaust elbow. If the flow through the exhaust elbow was ok last fall before the layup she should be ok now. But you could have lost a vane in your impeller, a bug got into the intake through hole, your belt is slipping on the pump, etc. Thats where I would look first. Good Luck Les s/v Mutual Fun
Gil, I would bet on something in the cooling intake line over the exhaust elbow. If the flow through the exhaust elbow was ok last fall before the layup she should be ok now. But you could have lost a vane in your impeller, a bug got into the intake through hole, your belt is slipping on the pump, etc. Thats where I would look first. Good Luck Les s/v Mutual Fun
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Tim Op't Holt
Overheating
Carbon build-up in the exhaust elbow is a good possibility. You can replace it yourself, see the pictures in the photo forum. Another possibility is the thermostat, which I replaced without difficulty and this reduced my high temperature problems. I suspect I'll have to do the exhaust elbow one of these days.
Carbon build-up in the exhaust elbow is a good possibility. You can replace it yourself, see the pictures in the photo forum. Another possibility is the thermostat, which I replaced without difficulty and this reduced my high temperature problems. I suspect I'll have to do the exhaust elbow one of these days.
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Tim Op't Holt
Pictures
Steve Dion posted the photo review of how to replace the exhaust elbow. You could also disconnect the water inlet elbow from the exhaust elbow, unscrew that small elbow, and ream the elbow out with a stiff wire. But, it's a temporary fix until you replace the main elbow.
Steve Dion posted the photo review of how to replace the exhaust elbow. You could also disconnect the water inlet elbow from the exhaust elbow, unscrew that small elbow, and ream the elbow out with a stiff wire. But, it's a temporary fix until you replace the main elbow.
Elbow is a common cause, but......
Gil: Tim & Bob are correct. This is a very common cause of overheating but I would check everything else first. Start at the Raw Water Strainer. Close the thru hull and pull the strainer out, be sure that there is nothing in the strainer. Then open the thru hull and make sure that water is flowing in freely. I had some gravel in the intake once. Next go the raw water pump and check the impeller. Change it while you are there regardless if YOU think it needs it or not. If the old impeller is still in OKAY condition, you can save it as a spare. Be sure to check the belt tension before you R/R the pump. If the belt is loose you may not be getting the proper cooling either. May as well replace the alternator and water pump belts at this time. Save the old ones as spares, for an emergency. The next place you can have a problem is in the heat exchanger. This area has raw water and anti-freeze in it. You can pull the front cover off and see if ALL of the passages are clear. If you can get some long Q-tips like that have at a Dr.'s office you can swab out each tube. I have not had the front cover of the exchanger off, so I do not know if you need a gasket or not. Be sure to check the thermostat too. The next place is the mixing elbow. As Tim mentioned I posted some pictures of the procedure. It is not difficult, just takes three hands. You need to make sure you have a gasket for the exhaust manifold, because there is a good chance that yours will not be any good once it is removed. The the last place if you have not found your blockage/problem is the exhaust hose. These can come apart on the interior and also get blocked. This is a difficult one to replace too but not impossible. A couple of other things to look at are your hoses. You want to be sure that the hose from the intake to the pump are not collapsing from the suction. If you hoses are soft this can happen and it will restrict the flow. I'm sure that you are going to find your problem somewhere in the system. If you do not then you will need to pull the head and see if there are any cracks. This is doubtful but would be your last resort.
Gil: Tim & Bob are correct. This is a very common cause of overheating but I would check everything else first. Start at the Raw Water Strainer. Close the thru hull and pull the strainer out, be sure that there is nothing in the strainer. Then open the thru hull and make sure that water is flowing in freely. I had some gravel in the intake once. Next go the raw water pump and check the impeller. Change it while you are there regardless if YOU think it needs it or not. If the old impeller is still in OKAY condition, you can save it as a spare. Be sure to check the belt tension before you R/R the pump. If the belt is loose you may not be getting the proper cooling either. May as well replace the alternator and water pump belts at this time. Save the old ones as spares, for an emergency. The next place you can have a problem is in the heat exchanger. This area has raw water and anti-freeze in it. You can pull the front cover off and see if ALL of the passages are clear. If you can get some long Q-tips like that have at a Dr.'s office you can swab out each tube. I have not had the front cover of the exchanger off, so I do not know if you need a gasket or not. Be sure to check the thermostat too. The next place is the mixing elbow. As Tim mentioned I posted some pictures of the procedure. It is not difficult, just takes three hands. You need to make sure you have a gasket for the exhaust manifold, because there is a good chance that yours will not be any good once it is removed. The the last place if you have not found your blockage/problem is the exhaust hose. These can come apart on the interior and also get blocked. This is a difficult one to replace too but not impossible. A couple of other things to look at are your hoses. You want to be sure that the hose from the intake to the pump are not collapsing from the suction. If you hoses are soft this can happen and it will restrict the flow. I'm sure that you are going to find your problem somewhere in the system. If you do not then you will need to pull the head and see if there are any cracks. This is doubtful but would be your last resort.
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Michael O'
99.5% strainer problem
I'll bet money it's either the strainer (which you can't see through the glass) or the hose coming into the strainer. This happens to me almost every summer. Seaweed or some other junk gets lodged in the hose just before it enters the strainer. I carry an old wire coat hanger for the sole purpose of reaming out this hard to reach area. Beware: since you need to leave the water turned on while testing this blockage, once the crud is gone, the gusher will start shooting water into the engine compartment! At least you know it's flowing. Let us know the outcome.
I'll bet money it's either the strainer (which you can't see through the glass) or the hose coming into the strainer. This happens to me almost every summer. Seaweed or some other junk gets lodged in the hose just before it enters the strainer. I carry an old wire coat hanger for the sole purpose of reaming out this hard to reach area. Beware: since you need to leave the water turned on while testing this blockage, once the crud is gone, the gusher will start shooting water into the engine compartment! At least you know it's flowing. Let us know the outcome.
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Scott Moore
Exhaust elbow...
I had an overheat problem last year, the source, a clogged exhaust elbow. I cleaned the elbow (the Tim Opt method mentioned in another response) and then flushed the cooling system with "Marsolve" (a biodegradable solvent). No problems since! Marsolve has a website and fact sheet...
I had an overheat problem last year, the source, a clogged exhaust elbow. I cleaned the elbow (the Tim Opt method mentioned in another response) and then flushed the cooling system with "Marsolve" (a biodegradable solvent). No problems since! Marsolve has a website and fact sheet...
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