UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

[wake5150]

Here's what I got fellas....<br /><br />Boat: 35' Tiara with two Inboard 454 Crusader XL, EFI FRESH WATER COOLED<br /><br />Port Engine idles and trolls (1500 rpm)fine with engine at 150F, but overheats quickly (4-5 minutes) on plane at 3000/3500 rpm.<br /><br />Side Note: Some steam coming from exhaust at trolling/idle speed. Usually indicates lack of sea water flow?<br /><br />Things Done<br />1) Replaced both elbows.<br />2) Inspected heat exchanger. All passages clean end to end.<br />3) Checked strainer. Clean as a whistle.<br />4) Removed seawater output side of oil cooler, ran engine at 1500 and 3000 in Neutral. Water flow seems "ok to me". Put hand over hose, pressure seems "ok to me".<br />5) Removed both seawater outputs of heat exchanger(last leg before going to elbow). Ran engine at 1500 and 3000 in Neutral. Water flow seemed "ok to me".<br />6) Put back together, Ran Engine at 3000 in Neutral for several minutes (at slip) and engine temp stayed below 170.<br />7) Removed Seawater pump for inspection. Impeller looks great, was replaced 1-2 years ago. Pump itself seems somewhat flaky, with obvious minor leakage out shaft seals. Some rust on outside of pump near shaft seals. Also with impeller removed, shaft seems very "loose" in housing, don't know if this is normal?<br /><br />What the heck am I missing here guys? I'm thinking the pump is bad and can't provide enough suction while on plane. <br /><br />Maybe the flow seems "ok" to me, but in reality isn't. How do you determine if flow is sufficient?<br /><br />Thanks For Your Help<br />-Chris

 

[Don S]

Re: UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

IF your raw water pump has leakage around the shaft and has that much play in the shaft, it's also sucking air instead of water, and pump bodies also wear out. May just need a new pump.<br />You also replaced the impeller a couple of years ago, was the old one without vanes. Have found a number of boats with pieces of old impellers blocking the water flow in oil coolers and heat exchangers.

 

[bigbrownbuku]

Re: UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

a clear hose test might narrow it down for you.

 

[wake5150]

Re: UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

Don,<br /> I think the old impeller was ok, with no parts broken off. If there were pieces in the oil cooler, it doesn't seem like the oil cooler is actually servicable? <br /><br />Question: We disconnected the hoses from the heat exchanger to the elbows. When we ran the engine there is a fair amount of exhaust that blows back through the elbows. I assume there will be some exhaust back pressure that the water pump must overcome?<br /><br />Also, there is a Muffler looking thing just before the exhaust leaves the side of the boat. Is it possible/common that these things get clogged such that they put enough back pressure on the exhaust system and subsequently on the water pump?<br /><br />Thanks again<br />Chris

 

[wake5150]

Re: UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

Anybody else have any other thoughts on this?<br /><br />Thanks again<br />Chris

 

[Bt Doctur]

Re: UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

what about the underwater pickups,<br />Are you sure you that hot,steam is not always an indicator of trouble on an inboard.impellers every 2 years regardless of how they look.<br />bad gauge, sender,bad ground.

 

[snapperbait]

Re: UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

I agree with BenC... <br /><br /> Use a clear hose between the output side of the pump and the oil cooler.... <br /><br />Fire her up and watch for bubbles... Bubbles indicate that your pump is pulling air from somewhere.. <br /><br />May be simple as a loose hose clamp..

 

[waterone1@aol.com]

Re: UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

First I would try to verify the "over heat". What is the gauge saying and are you sure this is correct ? Secondly, a raw water impeller that "looks good" may not be. If the vanes are weak or have a "set" to them, they may not get the job done when you are pushing the engine. If it has been 1-2 years since replacement, get a rebuild kit, complete with impellor, wear plate and "o" rings. If that doesn't solve the problem, it was time for it anyway and you can "rule that out".

 

[wake5150]

Re: UPDATE: FIXED: 454 Crusader Inboard Overheating at High RPMs

UPDATE: FIXED PROBLEM!<br /><br />The sea water pump seemed to have water pressure "ok to me", but obviously that wasn't the case.<br /><br />After taking the sea water pump off the engine it seemed that the shaft was "wobbly". While disassembling the sea water pump the bearings basically fell apart.<br /><br />Couldn't take the chance with upcoming trip, so bought new pump ($200). Also rebuilt old pump as backup. We didn't realize how "smooth" the pump should rotate when rotating by hand. It's amazing that the old pump could pump as much water as it was.<br /><br />Thanks again for suggestions<br />Chris