Twin FWC 454XLs. New water pumps (raw), new exhaust elbows. Manifolds are 5 years old, oil cooler is 5 years old as is the heat exchanger. Stud engine runs cool at all RPMs, port engine runs cool up to about 2500 rpm, and at idle. Above 2500 rpm, temp creeps pp to about 190 and steam out exhaust at that temp. Not losing antifreeze. Cools right down to normal when I back off the throttle. Thoughts? Thermostat?
Running hot
- Thread starter Gregory S
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- Joined
- Jan 1, 2000
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- 2006
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- 359
Which engine had the crossed hoses on the raw water pump? If it was the Port I'd replace the impeller and see if the symptoms change or remain the same.
- Joined
- Jan 1, 2000
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Oh Well
Cleaned strainer, back flushed U-cooler, tightend all hose clamps. Only thing I haven't done is pull the thermostat and back flush heat exchanger. Any suggestions? Haven't run it under load since I did those things.
If you can't indefinitely keep your hand very comfortably on top of the elbows (risers), there is a restriction or flow problem on the RW side.
Have you carefully cleaned out the RW main engine intake strainer-scoops? Strainers tend to get restricted with A/F paint and slots or holes should be cleaned each season before commissioning to permit normal flow. Fouling growth can build up in there too , which is why I switched all mine to the Groco ASC series with clean-out hatches which allow applying A/F paint inside.
Have you checked any RW basket strainers in the boat at the seacocks? Seacock fully open?
The suction side hose to the RW pump may be thin wall rubber with a supporting metal coil inside . That coil has disintegrated on pump suction hoses on my 5.7L crusaders several times when checked so the hose needed to be replaced to prevent potential suction collapse at higher flow demand .
A suction air leak ( loose hose clamp?) is another possibility, but that kind of leak is usually limited and even may tend to be somewhat self-sealing as greater suction pulls the hose tighter to the barb. Then again, greater hull STW rams more water into the pickup scoops , balancing suction if the scoop is not fouled.
Heat exchanger RW side debris restriction is possible. Did you find much debris when you back-flushed the coolers into a bucket? ( I often do.)
Do ever recall an impeller on that engine breaking up and not finding and removing all the missing pieces?
Have you carefully cleaned out the RW main engine intake strainer-scoops? Strainers tend to get restricted with A/F paint and slots or holes should be cleaned each season before commissioning to permit normal flow. Fouling growth can build up in there too , which is why I switched all mine to the Groco ASC series with clean-out hatches which allow applying A/F paint inside.
Have you checked any RW basket strainers in the boat at the seacocks? Seacock fully open?
The suction side hose to the RW pump may be thin wall rubber with a supporting metal coil inside . That coil has disintegrated on pump suction hoses on my 5.7L crusaders several times when checked so the hose needed to be replaced to prevent potential suction collapse at higher flow demand .
A suction air leak ( loose hose clamp?) is another possibility, but that kind of leak is usually limited and even may tend to be somewhat self-sealing as greater suction pulls the hose tighter to the barb. Then again, greater hull STW rams more water into the pickup scoops , balancing suction if the scoop is not fouled.
Heat exchanger RW side debris restriction is possible. Did you find much debris when you back-flushed the coolers into a bucket? ( I often do.)
Do ever recall an impeller on that engine breaking up and not finding and removing all the missing pieces?
Sometimes the riser gets clogged with rust and blocks the raw water from flushing freely.
Another, sometimes the raw water going to that side gets a little restricted. What little raw water going out the riser gets turned to steam from the exhaust. Feel the riser at different RPM's, is it too hot or bearable.
What and where is the restriction of raw water flow.
The balls and spring in the thermostat housing is a place to look. Too much spring pressure actually reduces flow. I tried pulling the spring apart but it didn't work. It reduces flow. Might be rust or something on the SS rod restricting free movement of the ball on that side.
Now if it was steaming at idle and slowed at higher RPM, I'd guess a riser manifold gasket leaking...or a very slight cracked head/gasket.
Another, sometimes the raw water going to that side gets a little restricted. What little raw water going out the riser gets turned to steam from the exhaust. Feel the riser at different RPM's, is it too hot or bearable.
What and where is the restriction of raw water flow.
The balls and spring in the thermostat housing is a place to look. Too much spring pressure actually reduces flow. I tried pulling the spring apart but it didn't work. It reduces flow. Might be rust or something on the SS rod restricting free movement of the ball on that side.
Now if it was steaming at idle and slowed at higher RPM, I'd guess a riser manifold gasket leaking...or a very slight cracked head/gasket.
Sandy, tried all those things. Never had an impeller break up.
Charlie, that's the $64,000 question. Where is the raw water restriction.
Bruce, impellers have always been intact.
The elbows on this engine are running about 140 degrees compared to the other side which run at 100. It's only the top of the elbow that's hot, ends and sides are about 100 degrees.
I ran the boat today and at cruise, that engine runs about 185 degrees while opposite was at 170.
Have any of you tried flushing the raw water side with Barnacle Buster.
Charlie, that's the $64,000 question. Where is the raw water restriction.
Bruce, impellers have always been intact.
The elbows on this engine are running about 140 degrees compared to the other side which run at 100. It's only the top of the elbow that's hot, ends and sides are about 100 degrees.
I ran the boat today and at cruise, that engine runs about 185 degrees while opposite was at 170.
Have any of you tried flushing the raw water side with Barnacle Buster.
This is a Crusader 454XL right?
Charlie , I don't believe there are spring-and-ball poppet style bypass valves in the T-stat housing . It's FWC ( "heat exchanger"mentioned).
But is it Full FWC ( RW only flowing through the elbows, after the SS block-off plate between gaskets ) or just 1/2 FWC( with RW flow through the ex. manifolds and elbows with no SS block-off plate , only gaskets between them)? If the latter, do you have the proper gaskets & in correct orientation?
Were the new elbows checked and cleared of any extraneous casting flashing in the water passages?I Crusader advises to do that. I always have to clear those out a bit where I can see them but not sure it makes that much difference there in a Full FWC engine exhaust system just before the RW inlet.
Charlie , I don't believe there are spring-and-ball poppet style bypass valves in the T-stat housing . It's FWC ( "heat exchanger"mentioned).
But is it Full FWC ( RW only flowing through the elbows, after the SS block-off plate between gaskets ) or just 1/2 FWC( with RW flow through the ex. manifolds and elbows with no SS block-off plate , only gaskets between them)? If the latter, do you have the proper gaskets & in correct orientation?
Were the new elbows checked and cleared of any extraneous casting flashing in the water passages?I Crusader advises to do that. I always have to clear those out a bit where I can see them but not sure it makes that much difference there in a Full FWC engine exhaust system just before the RW inlet.
- Joined
- Aug 1, 2002
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For what it's worth, I found a constant issue with my port engine running warmer to almost overheating about 10 years ago. I ended up removing the ball valve seacock and found the inside of the thru-hull fitting had clogged over time from barnacle growth to less than a 1/4" and restricting water flow. I simply chiseled this crud out, (while the boat was still in the water) added some sealant to valve and screwed back on, reinstalled intake hose and got the correct flow back. That was that...
Not a bad idea , but remove the pencil zinc inserts in the heat exchanger and coolers 1st & remember to reinstall after flushing the BB out.
Still suggesting placing your boat at a shallow section of a dock where you can stand on the bottom with a mask and waterproof light and carefully rake out the intake scoops (if slotted type) with a screwdriver tip to remove restricting paint buildup and growth.
At least you will know that part is no longer restricting flow. There is a good chance you can double potential flow capacity through those slots.
But if it is the perforated-screen type scoop strainer that would be tedious to clean well without a tank on.
Reel Antsy- How did you do that on your boat taking the seacock off for access while boat was in the water???
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Sandy, carefully and prepared.
I closed the seacock, removed the intake hose, slowly unscrewed the valve. Some water came in but I noticed it was not at a good stream. I scraped the inside of the thru-hull while some water was coming in. It wasn't real fast. I made a rubber hose with a capped end to slide over through hull stem every now and then to slow the water as I gained, let the bilge pump run a bit and scraped again. I had reservations at first doing it in the water but it worked.
I closed the seacock, removed the intake hose, slowly unscrewed the valve. Some water came in but I noticed it was not at a good stream. I scraped the inside of the thru-hull while some water was coming in. It wasn't real fast. I made a rubber hose with a capped end to slide over through hull stem every now and then to slow the water as I gained, let the bilge pump run a bit and scraped again. I had reservations at first doing it in the water but it worked.
Sandy, looked closely at intakes after bottom was painted 2 weeks ago. Didn't seem to be any restriction from paint. Got sme Barnnacle Buster today and a pump to circulate it. Now, to Lowes for fittings, hose clamps and hose.
- Joined
- Jan 1, 2000
- RO Number
- 2006
- Messages
- 359
Surgical tubing won't work? 