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| T O P I C R E V I E W |
| NORMinCONN |
Posted - Apr 19 2012 : 20:10:09
I am in the process of buying a 1989 Silverton Express with Crusader 454's. The starboard engine will run fine at no wake speed. Soon as I WOT it over heats. If I bring it back down to no wake speed it comes back down to normal temp. We have checked the impeller and that is fine. There is water flow because I do see water coming out from the exhaust. I think there is some kind of blockage. if you have any help please reply. Thank you. |
| 10 L A T E S T R E P L I E S (Newest First) |
| Kevdon22 |
Posted - May 12 2012 : 21:12:55
Most of the time it is the oil coolers when a crusader engine overheat.
My experience is that the U type coolers are hard to clean and replacement is often required.
Did you have to replace the coolers?
If not how did you clean them |
| jtybt15 |
Posted - May 07 2012 : 14:25:44
When you have some kind of obstruction on the intake side, running at higher RPM, over time, MAY cause insufficient water to get to the pump/impeller and cause early wear on the impeller. Just something to keep an eye on. |
| NORMinCONN |
Posted - May 07 2012 : 13:52:00
Update: It was the oil coolers. They were plugged up. I have to do the port side now and should be good as gold. |
| zane |
Posted - Apr 25 2012 : 11:17:51
If you follow sandy's directions you'll most certainly find the problem. Fwiw i had similiar issue once on my crusaders Found impellor had lost a blade. It was right in oil cooler. There is a screen there and its first stop for debris after raw water pump. |
| Thudpucker |
Posted - Apr 25 2012 : 10:35:35
Obstruction! Sandy hit it in the first sentence.
At some time the Sea Water pump came apart and pieces of that are lodged in the cooling system somewhere. Ask the P.O. about that.
Some body's gonna have to take stuff apart till you can use a hi-pressure hose to blow out the obstruction. |
| jtybt15 |
Posted - Apr 20 2012 : 14:51:52
I didn't read all of sandy's stuff, but, he usually touches on one or more of the likely causes.
Just from what you say, my first guess was worn raw water impeller or housing...or air leaking in at higher speeds. this can happen anywhere along the intake/suction side of the intake.
Basically, it comes down to insufficient water flow.
Oh, forgot to mention sticky thermostat. |
| mabbott |
Posted - Apr 20 2012 : 14:09:08
Sandy covered it all but......if you have sea strainers, make sure the cork gasket on the covers are good and the covers aren't sucking air. |
| Sandy |
Posted - Apr 19 2012 : 22:18:03
If FWC, find out when the last set of new riser/elbows was installed. If not within the last 5-6 yrs it's time. Even if fairly new, it's possible a previous impeller lost part of a vane that ended up restricting something downstream including the riser/elbows and flow is still sufficient almost up to WOT.
Is there steam in the exhaust? Are your exhaust outlets in a position where you can observe strong flow at WOT ?
How long can you hold your palm on the riser/elbow at higher rpm? If you can keep it there , look to the FWC side if appropriate. I expect it will likely be hot.
If you want to check RW pump output, I believe Crusader specs 5 gallons pumped in 15 seconds at 4000 RPM. But I cringe at the thought of trying that. But on a cool engine, flow out of one hose to an elbow might be say somwhere near 0.83 gal in 10 seconds at 2000 RPM if I extrapolated that correctly. Unfortunately that latter mght not prove much since it only overheats at WOT.
The coolant cap pressure for all models back then was 7 psi , in case that has been replaced. FWC thermostat was 160* F.
Check the RW intake scoop strainers. My boat is still on the hard for a few more days and I just spent some time under the boat with a stiff thin blade scaping out excess paint in the slots and fairly substantial calcium buidup above the slots, restoring potential max flow there. Wish I had the "Great South Bay type" intakes with removable section for cleaning. Of course check any RW basket strainers at the seacocks, making sure they are clear and lid seal is doing it's job.
I backflush my crankcase oil cooler and heat exchnger at least once a season with dock hose and simple adapters I made up . My blue 5.7 L's don't have transmission coolers but add that to yours. It's surprising the size of the lettuce that gets flushed out sometimes. When I pre-emptively replace elbows I remove the main heat exchanger endcaps and inspect the bundle tubes with light and rod. So far they've been clean. I pull the hose from oil cooler to RW pump and rod out the bundles in there too to check. Good so far.
There is usually a removable support "spring" coil inside the suction hose leading to the RW pump intake. I've had several of these disintegrate from corrosion , and that not only adds to the liklihood of pump damage but also potentially allows that hose to collapse under highest suction of higher rpm and possible contributing hull intake restriction. On mine the big hose leading from the bottom side of the Main heat exchanger back to the suction side of the engine circ pump also has a support coil, since it is in coolant mix it doesn't corrode put Crusader told me the long term flow can cause the H/Ex end of that coil to migrate away from that end and leave that unsupported section vulnerable to collapse or restriction too. I've restretched and repositioned those coils a couple times after discovering they had migrated 6' or so , but never saw signs of collapse there yet. Check to see if any RW or FW side hoses are crimped restricting max flow.
If the boat was just put in the water after spring commissioning, there is always the possibility of air pockets in the FW side of a FWC system that might need purging to stop overheat & hurling.
If FWC, were coolant overflow reservoirs added to that 1989 system so any overflow can automatically be recaptured by the engine as it cools? I quickly added those to my old 1988 Crusaders. Newer Crusaders have a much better system that includes the Degas bottle with coolant constantly running through it for constant air purge.
This doesn't sound like a thermostat problem but keep it on the list. Check belt tightness too to rule out pump pulley slip. i think it's usually max 1/2" deflection on most Crusaders w/o serpentine belts.
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| foggysail |
Posted - Apr 19 2012 : 20:30:35
quote:
Originally posted by cwms
Assuming it is FWC, the manifolds are probably good, but the risers might be shot. Also, the heat exchanger might be all clogged up.
Regardless, it's up to the seller to make things right before final purchase.
Also the oil coolers have an impact. My heat exchangers were sooooo plugged, I had to rod them using a SS welding rod. Tried the radiator shop routine first............useless! |
| cwms |
Posted - Apr 19 2012 : 20:26:40
Assuming it is FWC, the manifolds are probably good, but the risers might be shot. Also, the heat exchanger might be all clogged up.
Regardless, it's up to the seller to make things right before final purchase. |
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