Engine overheating problem - Maxum Boat Owners Club

tjwieseler · 05-17-2010, 03:12 PM

I purchased my 1997 2400 SCR in January, so no water test. Purchased from a reliable seller, at least he seemed to be. The boat looked like it was very well taken care of, and only 500 hrs on her. I have taken her out for probably 30 hrs or so without a problem. Then Friday I had it at full throttle and it started to overheat, so I backed down on the throttle and it cooled off. So I was going to look into why it was overheating, but had friends coming out on Saturday to go boating. We took off and got 10 miles from our dock and decided to anchor for a while. On the way back to the dock I brought the boat up on plane at full throttle and noticed the temp getting up there (200) so I backed it down to 3400 rpms and the temp was showing 150 I kept it at this rpm for a while and noticed that when I tilted the trim up the temp would climb again, so I left it down and the temp stayed right at 150. Then all of a sudden I noticed a loss in power, and I tried to give it a little more gas and it wouldn't pick up rpm's so I shut her down. When it reached 1000 rpms I noticed the temp guage was pegged at 250 and the engine was knocking. I immediately shut her off and she wouldn't stop running, it dieseled for a couple of seconds and then quit. We were towed back to the marina, where I started her back up to get into my slip. She ran just fine, oil pressure came up and everything seems fine for now. I checked the dipstick and looked in the valve covers for any sign of water in the oil and didn't find anything.

Any ideas what the problem could be? The previous owner just had the impeller changed when I picked it up, and made me pay the bill from the shop. So it shouldn't be the impeller. I was told to check the thermostat, and the oil cooler for possible impeller parts plugging it up.

I really don't want to taker her out of the water, but I can do whatever I need to do.

ss3964spd · 05-17-2010, 03:57 PM

Bummer. Has the engine always run at 150? If yes, that's too cool and suggests that either the wrong t-stat is installed or the t-stat is getting stuck too far open. Could be that the gauge isn't correctly calibrated so verify by getting the engine to operating temp then shoot the t-stat housing with a hand held IR thermometer.

However, having the temp go up when tilting the drive up suggests the impeller - especially if you've never seen that symptom before. If your drive has one it could also be the raw water hose from the drive to the engine is loose or has a crack in it and tilting the drive up creates more of a leak in that hose.

Could be clogged exhaust risers - which would be a buzz kill, but you can help diag that with the IR gun.

Some good reading here: http://www.sterndrives.com/overheating_problem.html

Dan

tjwieseler · 05-17-2010, 04:08 PM

The boat normally runs at 175-180. Someone told me the 150 could have been because there was NO water in the thermostat housing.

The raw water hose was replaced when I replaced the bellows before putting on the water, but I am also wondering if maybe it came loose and tilting the engine was allowing it to come off, and then it finally came all the way off. I will have to go swimming in 62 deg water or take it out to check.

ss3964spd · 05-17-2010, 04:40 PM

Someone told you correctly. If the temp sensor isn't in water then it can't read the water temp. Does not fit though - since you mentioned that you saw the temp gauge pegged at 250.

When you did the drive tilt test, was the symptom repeatable? Meaning, were you able to tilt the drive up several times with the same results? If yes I'd be focusing on the raw water pump or hose.

I'd be pulling the boat, because I don't like cold water. Also, if you are able to actually see the problem underwater are you going to be able to fix it underwater? Under cold water?

shrew · 05-18-2010, 02:35 PM

1) Manifolds. It's Possible enough scale has clogged passages, but only enough to restrict water flow. At lower RPM's waterflow is enough to cool.

2) Impellor. Similar. It may still be pulling water, but not enough at higher RPM's to maintain lower temps.

3) How long has the boat been in the water? I had a similar issue late last year where barnacles were blocking the pickups in the outdrive. The restiction was enough so that the engine temp. only rose at higher RPM's. This was because I stupidly covered the pickup holes with masking tape before I primed and painted the drive with anti-fouling paint. The holes were the only thing on the drive without anti-fouling and the only place the barnacles grew. (I didn't try to run on plane with the drive completely in, so I don't know if I had that specific symptom).

Just a few thoughts. Engine overheating is a common issue, and this is where I would start looking.

By the way. If the engine dieseled, you may want to do an oil change and see what the oil looks like. If it's anything but black (particularly if it looks like coffee with cream) run about 5 or more oil changes through the thing. It's my understanding that a it's possible for a 'dieseling' engine to actually run in reverse and suck water up the exhaust. That would be les than desirable.

edrey1996 · 05-19-2010, 01:16 AM

I had this same problem with my boat . the problem was 2 things. first I had my impeller change. just out the shop . and at slow idle the boat ran fine, then when i raise the rpm the motor will get hot, 220 hot ! ! so i taken the out drive off, and found the hose that went to transom housing there is a water hose, it was kink . just enough to let some water throw, but not enough . so i replaced that hose. and after i cut that hose off. i found some of the old impeller in that hose and in the metal hose . with some long nose pliers. i pulled out some more impeller. Then went inside the boat. taken off that hose in back of the motor and blow some air with my compressor . a little more impeller came out . put it back together . That was the problem.I hope this story help you . it sure help me . PS. i think if you get under your boat and look up by the bellows yous should be able to see that hose. transom housing to the out drive it's a 3/4 or 5/8 hose

tjwieseler · 05-19-2010, 12:32 PM

That is one of the things I will be checking. We just changed the bellows and the raw water hose before putting it in the water. I am thinking that it could be twisted or maybe came off???
Is your outdrive an Alpha or Bravo? I was told by a Merc mechanic that the Alphas usually do not break pieces off of the impeller.

seapuppy · 05-19-2010, 05:35 PM

sounds like an impeller problem....plus...remember the temp sensor is on the stbd side of the engine...down in the block..I don't believe it's in the thermostat housing...

SP

Bella Sera 3300SCR · 05-19-2010, 05:50 PM

one other thing to consider, is the past boat use and geographic location; boats that don't get winterized as a result don't usually get the block bung drain plugs removed letting the accumulated sand and tubidity out. Sand/dirt gathers in the waterjackets especially if the boat is beached. Which is why I do not over idle my 350mags while on shore. I know that a lot a crap comes out of my mills when I drain the blocks during the sad lay up process. That junk will otherwise settle and displace vital cooling area which can cause the aformentioned over heating while under way but not while idling.

Bella Sera

edrey1996 · 05-19-2010, 10:04 PM

it was a alpha 1 out drive. and if you get the impeller hot enought it will come apart . my boat was sterted with no water ! yes started dry !@ well i bought it like that. it was a used boat . you just don't know what the person did befor you bought it .and when you check the raw water hose, turn the sterring wheel both ways, all the way . i think when i turned left, that was the worst on the hose.

tjwieseler · 05-22-2010, 12:45 PM

Well everyone, thank you for all of your responses, but I don't have to worry about why it is overheating. Yesterday I replaced the thermostat and decided to take her out and try to see if it would overheat. It started and idled just fine, except I did notice it burning oil, which it didn't before. I took it out on the lake and brought the throttle up and there wasn't the power it had before. Also when it reached 3000 rpm's it started a loud clanking noise and wouldn't get any more than 4000 rpm's. I just backed it down and brought her back to the slip.
Sounds like a new engine is in order and I really don't have the $$ right now.

Anybody know of any good, cheap long block marine engines?

seapuppy · 05-22-2010, 02:42 PM

sorry to hear about the engine going on you....sure puts a damper on your summer....

about the best I've heard for support on marine engines is Michiganmotors.com

I'm sure there are others but I can't remember them right now...I've known people go thru michigan motors and been very happy...

SP

Tommyfmu · 05-22-2010, 02:55 PM

< no expert on engines at all, but a few things came to mind before throwing in the towel. If the power won't get above 4k rpms, maybe all 8 cyl's aren't sparking resulting in the loss of power, which may be resulting in the smell you're smelling ; unused gas being sent out of the exhaust ports (?). How new are the spark plugs, and are they gapped correctly? Changing them out may be one thing to try, certainly a lot cheaper than a new engine. Also in my novice diagnosis, are you seeing any oil leaking into the bilge indicating a crack in the block, and conversely is the exhaust blue indicating oil burning? I'm thinking the sound at higher rpm's may be rods hitting the oil cover possibly due to lack of oil, but it has to be going somewhere (?). Also may want to compression check the cylinders; maybe a piston ring on one or two is failing. ok, enough from this amateur, I just hate to see a few thousand $'s spent for something remedied for a few hundred $'s.

Bella Sera 3300SCR · 05-23-2010, 02:34 PM

Quote:

Originally Posted by tjwieseler

Well everyone, thank you for all of your responses, but I don't have to worry about why it is overheating. Yesterday I replaced the thermostat and decided to take her out and try to see if it would overheat. It started and idled just fine, except I did notice it burning oil, which it didn't before. I took it out on the lake and brought the throttle up and there wasn't the power it had before. Also when it reached 3000 rpm's it started a loud clanking noise and wouldn't get any more than 4000 rpm's. I just backed it down and brought her back to the slip.
Sounds like a new engine is in order and I really don't have the $$ right now.

Anybody know of any good, cheap long block marine engines?

Another good rebuilder is doug russel marine http://www.dougrussell.com/Products/...cts&Category=6 , they offer pretty good prices on rebuilt and new mills both short and long although I would strongly suggest that you go with the block and heads together. otherwise its like putting powder on a pig.
good luck with getting back on the water.

Bella Sera

seapuppy · 05-23-2010, 05:45 PM

I read this first thing in the morning ..so my answer wasn't quite awake....first off..have you done a complete analysis and trouble shooting process to really find out what is going on???...might wanna do a compression check...pull plugs to see how they are burning..check gaps...check the distr. cap..rotor...wires...etc.....before throwing in the towel...do a complete trouble shooting process and get back too us...

SP

edrey1996 · 05-24-2010, 08:34 PM

i used a company called Jasper 1/800/827/7455 they sell out drives and motors, this is a motor exchange comp. it don't hurt to check prices !

tjwieseler · 05-28-2010, 09:18 PM

Hey SP, or anyone in the Washington area. I found two companies I am thinking about buying an engine from. They are S and J engines out of Spokane and US Engines out of Kent. Can any of you tell me anything about these companies. They both offer a good quality engine at a reasonable price. S and J has a 5.7L for my boat that would run 1518.00 plus core and shipping. US Engine offers one for 1925.00 plus core and shipping, but what intices me is they have a 300 HP 5.7 that would replace mine without any intake or fuel changes plus a 7 year warranty! They claim 25% less fuel usage.

Any help would be appreciated. They are a long ways from Des Moines, IA!!!

ss3964spd · 06-01-2010, 12:35 PM

25% less fuel usage compared to what TJ?

If I had to re-power I'd want to see a complete listing of the parts used in any rebuilt engine, to what tolerance the rotating assembly was balanced, as well as the torque curve of the engine.

You might also consider a 6.2/383 engine that is based on the 5.7/350. Same external dimensions but they come with sizable torque increase.

Dan

tjwieseler · 06-01-2010, 08:05 PM

25% less then the stock 5.7

Yes, I agree. I will see what they say. They do offer a 7 year guarantee, but they are 1500 miles away.

I would love to do the 383/6.2, but I don't think the Alpha One could take the horsepower and torque.

ss3964spd · 06-01-2010, 11:06 PM

Ah, you may be right regarding the A1 drive.

They are claiming their 5.7 is 25% more efficient than the stock 5.7? That's significant and in my mind suspect, so I would definitely want to know how they do that with no reduction in Tq.

Sorry, I know it seems I'm being negative, but the 7 Yr guarantee will be meaningless if they are 1500 miles away and that engine develops a health issue requiring removal and shipping. Do they cover the R&R and shipping cost? If you buy the engine from them, but someone else installs it, will you get caught up in a finger pointing contest between the installer and the builder saying the other caused the problem?

Just some things to consider.

Dan