Engine temps running high
- Thread starter harmsway
- Start date
Raw water cooled or freshwater cooled? If fresh water cooled, have you ever cleaned out the raw water side with something like Barnacle Buster? Are you making more steam than usual? Both engines? How long since your thruhulls, strainers cleaned out? If fresh water cooled, are you running 50% antifreeze? Higher concentrations provide more freeze protection but don't cool effectively.
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- Sep 16, 2003
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Heat exchanger issues usually get gradually worst, often a sudden change i more liekly to be impeller although i peller pieces end up at the HE inlet.
When changing the impelleer, make sure you check the HE inlet and retrieve the pieces
When changing the impelleer, make sure you check the HE inlet and retrieve the pieces
- Joined
- Sep 23, 2002
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I have similiar issue. Normally both diesels run at 185, but lately I was noticing them creeping up.
I had overtemp marine do a flush with barnacle buster.
They also changed the impellers.
One impeller was slightly chewed up.
After the cleaning my cruise is now 185 on both motors, so there was an improvement but when I go to WOT they creep up or even just going slightly over my cruise RPM of 3150 it goes up. I have digital so it jumps from 185 to 196 because that is how it is designed, need to hookup voda tool to see actual temp.
Sound like your issue is similiar to mine, high speed overheat. I am told it could be two things now.
1) The water pumps may be scored reducing their efficiency.
2) Aftercoolers have some grass or blockage, but I did just backflush.
Another idea is the water temp is very warm here but I tend to not go for that. At WOT I get up to 202 on one motor and 196 on the other. So one motor definately running warmer than the other.
Last time i had this issue I had the whole raw and fresh side broken down and cleaned. Cost was $6K but it solved it. That was 4 years ago.
Hate to do that every 4 years.
By the way the eel grass by mean has a tendancy to get past the screens and into the motors.
We have some fine pieces like regular grass.
I had overtemp marine do a flush with barnacle buster.
They also changed the impellers.
One impeller was slightly chewed up.
After the cleaning my cruise is now 185 on both motors, so there was an improvement but when I go to WOT they creep up or even just going slightly over my cruise RPM of 3150 it goes up. I have digital so it jumps from 185 to 196 because that is how it is designed, need to hookup voda tool to see actual temp.
Sound like your issue is similiar to mine, high speed overheat. I am told it could be two things now.
1) The water pumps may be scored reducing their efficiency.
2) Aftercoolers have some grass or blockage, but I did just backflush.
Another idea is the water temp is very warm here but I tend to not go for that. At WOT I get up to 202 on one motor and 196 on the other. So one motor definately running warmer than the other.
Last time i had this issue I had the whole raw and fresh side broken down and cleaned. Cost was $6K but it solved it. That was 4 years ago.
Hate to do that every 4 years.
By the way the eel grass by mean has a tendancy to get past the screens and into the motors.
We have some fine pieces like regular grass.
I'm assuming it's both engines. I 'd start looking for a raw water restriction. Start at thru hulls and work back. If thru hulls, strainer and oil cooler are clear I'd flush with barnacle buster. In my experience, weak impellers show a problem at lower RPMs.
180 isn't high at all. Fresh water cooled should run at 180...it's more efficient at higher temps. What thermostat do you have? Could be the balls are sticking in the therm housing. How old are the ex manifolds? Do you run in fresh water or salt? ...and that impeller check is another good observation. LOOOOOTS of possible causes.
I believe the manifolds were replaced in 2014. I only run about 30-40 hrs per season or so in salt water. It's what I call " gently used" . So you're saying 180 is normal and I shouldn't worry until the alarm sounds?
I'm trying to avoid any major expense as I'm trying to sell.
I'm trying to avoid any major expense as I'm trying to sell.
Yep, 180 isn't high unless as you said your engines normally run at 160. So something is going on and I think you're right to address it before it becomes a major issue. I know with my engines, when I see a change in that direction something is happening and it usually isn't good.
With the engine nicely warmed up, put your palm on the top of the riser at idle rpm and at cruise rpm. With a healthy cooling system , the risers should feel cool or warm , not too hot
....If.... it feels too hot to comfortably hold your hand there indefinitely , that is a basic indicator the RW side has insufficent flow, so for now at least, ignore the FW side of the system and track down and fix the RW side. ( Likely either a RW flow restriction, RW pump has inability to pump water as it should, or there is a RW-side suction air leak before the pump.
If the riser top is comfy, fix the FW side.
....If.... it feels too hot to comfortably hold your hand there indefinitely , that is a basic indicator the RW side has insufficent flow, so for now at least, ignore the FW side of the system and track down and fix the RW side. ( Likely either a RW flow restriction, RW pump has inability to pump water as it should, or there is a RW-side suction air leak before the pump.
If the riser top is comfy, fix the FW side.
- Joined
- Jul 27, 2001
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in my experience, most common cause of high temps has been clogged intake, but that’s with bravo drive and it’s horrendous intake hose design.
Next up is clogged risers. I guess I don’t replace those nearly as often as I should. What’s the expected life in salt, five years? Sometimes when I know mine are about toast, and need to get another month or so out of them to finish a season, I soak them in acid to clean out the rust. That’s usually been good for a 10 degree drop on a hot engine if clogging is the issue.
Next up is clogged risers. I guess I don’t replace those nearly as often as I should. What’s the expected life in salt, five years? Sometimes when I know mine are about toast, and need to get another month or so out of them to finish a season, I soak them in acid to clean out the rust. That’s usually been good for a 10 degree drop on a hot engine if clogging is the issue.
There are a lot of narrow passages in the risers. Rust scale builds up and reduces flow. Inspect them every couple years. If they're clogged with rust, the traditional fix is to rod them out then soak in muriatic acid. "Rodding out" involves getting a 1/8" welding rod dig it into the rust growing on the walls of the riser. If there's a lot of rust, it'll flake off. Just shake all the rust flakes out as well as you can. It's not necessary to soak in muriatic acid (swimming pool acid treatment from hardware stores). It depends how long you want to keep the cast-iron parts in service...or just replace them.
The impeller is also a regular inspection/maintenance item. GVP (George) used to say change impeller every 2 years but I let it go a couple more.
The impeller is also a regular inspection/maintenance item. GVP (George) used to say change impeller every 2 years but I let it go a couple more.
- Joined
- Jan 28, 2004
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I have also noticed a slight increase in temperature but attributed it to higher water temp in the bay, 82 degrees the other day. I'm also FWC. I did impellers, thermostats and cleaned out the heat exchanger before splashing in June. One thing it could be in your case is a restriction due to seaweed as you know there's plenty of it now! If you have a strainer check it or pull and end cap off and see if its restricted there.
You should pull the inlet side of your U cooler and stick a shop vac to the inlet and pull out any debreeze blocking the screen. I do this every year and you would be surprised at how much crap is in there. Also I change the impellers every 2 years. I too have 454 crusaders.