Overheated ... pretty bad ...

[southkogs]

Need a little advice or perhaps confirmation that I'm doing the right things (still mediocre with a wrench on my best days):

'72 OMC 165HP - Stringer - Chevy 250 I6

BACKSTORY:
Been runnin' the boat quite a bit this year and she's been going just fine. Went out on the lake late Saturday and pulled out of the marina - no issues. Cranked her up and took off on plane (not WOT) and within 15 minutes the engine shut down and wouldn't re-start. I goofed somewhere and wasn't paying close enough attention to the temperature gauge and it had overheated. Spiked over 200. :facepalm:

I enacted the tow service I decided to buy this year - which worked very nicely :thumb: (oh, and the new VHF handheld works too ) - and by the time we got back to the dock, the engine would turn over. Put it on the trailer and hauled it home. Tried it one more time and it would idle (had it on for about 5 seconds). Oil looks pretty nasty dark, but not milky.

TO DO LIST:
Stern drive is off and I'll get a new impeller - I'm assuming something happened to it. Not sure, but I was gonna' change it out this year anyway.
I'll check the thermostat and water pump and make sure I am moving water through the system.
I plan on doing a compression check to see if the head gasket is good.
Once I push some water through it on the hose, I'll re-check the oil and see if it's milky.
Oil change.

What else do I need to look at? I'm not sure what to check beyond the above. I don't wanna' go crackin' stuff open that I don't need to, but I don't wanna' kill the thing either. I've got a couple other projects I may take on while I've got her in dry-dock so I'm not afraid of doing a little extra to do things right.

Thanks in advance.

 

[redneck joe]

I worry about not having an alarm on mine, and I do creep up when running for an extended time. Can you add an alarm to these old motors?

 

[vinnie1234]

Hey southkogs, I wouldn't worry too much about this. Most of the problems that occur in modern engines are the result of a cast iron block connected to an aluminium head. Aluminium expands at 1.7 the rate of iron, and is therefore prone to gasket failure and cracking while overheating as the block does not expand as much as the head and the block is much stronger. If I am correct in my assumption - you will have an all iron engine.

It is possible that with the overheating there may have been some scoring in the cylinder wall or damage to rings, which a compression test will tell you if there was a serious failure but at the end of the day if there is enough compression to run it, you will probably be able to do so without any problems, as long as you cure the overheating condition.

My advice is to fix the cooling issue and run the engine. If it seems to run fine and has adequate power - then it is what it is.

You should (of course) change your oil and filter. You will also want to monitor your oil pressure guage as this will tell you if there was any substantial problems with bearings.

Once the engine is running, you could also have a listen for abnormal mechanical noises with a stethoscope. Lifter noise, bearing noise and piston slap, but if you don't hear anything weird - just put er in the water and go for it.

 

[vinnie1234]

I am sot sure what the head bolts are made of on these things, but if you really smoked'er, it is possible that the head bolt tension has changed. Probably not, but backing them off and re-torqueing may not be a bad idea, but before doing this maybe check with a marine mechanic. He may have experience with this and can tell you if the bolts can be a little brittle. If so, then the re-torquing procedure may result in a snapped head bolt.

If unsure about that, and if it were my engine, I would set a torque wrench to the correct spec and run around all of the bolts and make sure they haven't backed off. A correct re-torque would require loosening and removal of the bolts, lubrication of the threads with oil, and re-installation.

If you were to remove them, don't remove all of them. Take the torqueing pattern from the manual and divide in in half, Take half the bots out, lube'em - put em back in (good and snug say 6 or 8 foot pounds) and then do the other half the same way. Then re-torque using the procedure in the manual.

 

[southkogs]

I worry about not having an alarm on mine, and I do creep up when running for an extended time. Can you add an alarm to these old motors?

Not sure ... and I'm probably not the one to know for sure. I usually keep pretty close watch on that gauge. I was letting the son of my friends drive the boat after we got out of the marina, and I just didn't look at it for this run. Generally it holds good and steady at 160 degrees ... not this time.

 

[southkogs]

Thanks Vinnie, I'll add all of that in. I'll get to workin' on it this week and report back in. Any other advice is welcome!

 

[vinnie1234]

For now, while you are waiting for time to work on it, take out the spark plugs and squirt a few tablespoons of automatic transmission fluid into each of your cylinders. let it sit for a few days. If there is any gunk in the rings (and there probably would be from normal operation), that will free them up. Before you try to turn it over, put rags over the spark plug holes and blow out the tranny fluid to prevent a hydrolock. YOu may have a hard time staring it, and you will have white smoke for quite a while after starting it up, but that is okay. wont hurt you at all - it will just freak you out.

 

[HT32BSX115]

within 15 minutes the engine shut down and wouldn't re-start. I goofed somewhere and wasn't paying close enough attention to the temperature gauge and it had overheated. Spiked over 200

Howdy,


That 250 L6 is probably one of the best engines ever put in a boat!

By "wouldn't re-start" do you mean it wouldn't turn over with the starter? OR it cranked and wouldn't run?

If it only went "over" 200 degrees, (not 260!!) you didn't "hurt" a thing with the overheat by itself.......if there was NO water in the block and head, it's possible that it got hotter and the gage didn't register it.

YES, you can get an over temp switch and install an alarm.

What else happened? Did the oil pressure drop to dangerously LOW levels and did the engine slowly lose RPM and then quit or was it an abrupt "quit"?

I am trying to determine if the engine overheated and slowly started seizing! Was there a LOT of smoke in the engine compartment (REALLY HOT ENGINE) etc etc.....?

Cheers,


Rick

 

[southkogs]

^^^^ Thanks Rick:

No smoke in the engine (well any more than normal, my exhaust manifold is leakin' a little). Oil level was (still is) good - just looks dark, but not milky. Gauge only reads up to 220, so all I know is it spiked. The quit was pretty abrupt/sudden, but not a boom or a slam. Engine just stopped and the boat settled into the water. At that point when I turned the key, the starter engaged, but didn't turn the engine over (thought I seized it). By the time we were towed back to the ramp, the temp was down considerably so I decided to risk trying to turn the engine over again - it did turn over (not seized), but I didn't let it start.

Towed it home on the trailer and then tried starting again, and it did start and idle (only let it go for a few seconds).

When I first popped the hood on it there was very little smoke/steam and a little bit of a sizzling sound where that manifold is leaking (bad gasket job by 'yours truly'). Nothing in the compartment seemed out of place, nor was there a bunch of water (again out of the norm) in the compartment as though the circulation pump or one of the hoses let go so I'm assuming they're okay for the moment. Belt was good (just replaced that last year and it was the second place I looked).

 

[vinnie1234]

Your biggest worry here is the piston rings. Most likely the rings overheated and you lost compression. A compression test (wet/dry) will tell you if your rings are fubar. How bad? Depends on compression. You may also have some scoring in the cylinder wall which will also affect compression because it prevents the ring from sealing.

Not to oversimplify this, but either you have wrecked or engine, or you haven't. If you do have a compression issue, it may be the result of minor scoring in the cylinder wall (from overheated rings), and the rings may refinish the surface of the cylinder wall if they are capable of applying normal pressure once it runs again. It may also be because the rings have lost their tension.

We know that your engine will start. So, aside from anything out of the ordinary (knocking clinking loud ticking or explosions) your best option is to start it and run it for a while - see what happens. And yes, I was kidding about the explosion part.

When you get time to do the work, and turn it over to get the tranny fluid out of it, start it up and let it run. Disconnect your throttle linkage so you can give it a series of quick full throttle blasts (to burn out the tranny fluid and force the rings to expand). Once it is warm, and you no longer have white smoke from the transmission fluid (hope you don't have blue smoke from oil) you can do your compression test.

Test all of the cylinders dry, then put oil in and check the difference. To do this, I squirt an ample amount of oil into the cylinder and then turn it over with the plug out to leave just enough inside to seal the rings. If you put too much in you will get hydrolock. Do your compression test with WOT and all plugs OUT.

The results of your compression test can give us an idea if you have a weak cylinder, worn piston rings or if you have a horseshoe up your heiny.

I really think you are on the right track, and I understand the need to be thorough, as I am sure you know because you have read enough of my posts to know I am a crazy bugger that way.

I really think this is a simple one. Either you wrecked it, or you didn't.

 

[southkogs]

Thanks Vinnie. I'm actually not that worried about it ... this is more recon for a guy who doesn't exactly know what he's doin'. Worse case is that the engine is toast and I've gotta' do a gut check on the boat. It'd screw up this summer and maybe next, but not that bad.

Broke upen the upper tonight. The impeller doesn't look bad but it was bone dry. There was water in the drive (like there's supposed to be) and it came out when I lowered it down off the trunions. I have an impeller, but not the whole service kit so I'm gonna' order the whole kit in.

Had a buncha' water in my upper gear case though - Yikes! I thought I had just changed that lube out.

I drained the engine block of water and it all looks clear. Oil still doesn't look milky. I've gotta' borrow the tool do the compression test, and I'll do that tomorrow night.

 

[HT32BSX115]

The quit was pretty abrupt/sudden, but not a boom or a slam. Engine just stopped and the boat settled into the water. At that point when I turned the key, the starter engaged, but didn't turn the engine over (thought I seized it).

It's very possible that the abrupt shutdown briefly hydrolocked the engine..........probably why it wouldn't "turn-over".......pretty common when the engine quits or someone turns the key off while underway at planing speeds.

I'll also agree, it's either "toast" or it isn't. (and it probably isn't!) Just hook everything back up (hoses and all,) make sure you have a functional raw water pump and there's no blockage and give it another try!

I am a little concerned about the water in the drive though........that *should* be completely unrelated to the engine failure unless the drive seized (which WILL absolutely stop an engine!)

 

[southkogs]

I am a little concerned about the water in the drive though........that *should* be completely unrelated to the engine failure unless the drive seized (which WILL absolutely stop an engine!)

LOL - me too! When I drained it out a couple weeks back it was fine. I've actually got a reserve upper ... just haven't looked at it in a bit. I was able to idle the engine before I took the drive off, so I know it's not locked up (mostly). I'll get checking that thing out too.

Thanks Rick.

 

[Lou C]

I had something similar happen last summer. The small hose from the inner transom plate to the P/S cooler popped off and overheated the engine AND filled the bilge up with salt water faster than you can say OH ****!!!
I thought the boat was taking on water through the bellows and the engine overheated, two unrelated things. I stopped and saw how full the bilge was, and as hot as the engine was then there was no way I was going to get back there to see what happened. I tried to get her in closer to the shore because the stern was getting really low in the water (starter under water, pulleys running in water) and the engine just dies. But then, the water stopped coming in, so it all made sense. By the time Tow Boat US came (only 40 min) the bilge pumped itself out. Got the boat out of the water, replaced:
Starter, full of salt water
flappers, vaporized
exhaust hoses, not burned but 25 years old
water tube gaskets in the outdrive, to be on the safe side
I took off the manifolds, to check for cracks with acetone. Fine too. Just for the heck of it, while waiting for the tow, I took out my IR temp gun (keep one on the boat, it makes it easy to do diagnostic work) and the manifolds read.....375*F....the block....225-250....which I guess is why....the engine was actually OK....

Started engine expecting to hear bad noises and smell smoke and....it starts....runs....normal temp....oil is clean....normal oil pressure....compression test (hot) normal and about the same as the last time I checked it 3 years ago. Ran it the rest of last season (this happened a year ago) and it was fine. Ran it this season, fine. I guess I got lucky. Cast iron engines are pretty forgiving, but this is the original engine, now 26 years old. So I'd change the oil, do a compression test and see what happens.

Now as part of my get ready routine, I go over every one of the hose clamps, INCLUDING that almost impossible to reach one on the back of the engine....sucker just popped off....

here's the ironic thing...I had a mild hot running issue for a few seasons, never more than 180 but it used to be 160. Figured out it was barnacles growing on that plastic intake screen in the lower unit. Well that spring I cleaned out the water intake area, there were barnies in there... and I did not replace the screen because that would have happened all over again here in salt water. BTW, neither Merc nor Volvo use screens on their I/O water intakes. Well that much better water flow...and the powerful Cobra impeller in the drive....probably helped pop that damn hose off...LOL....now the engine runs perfectly cool at 160....

 

[southkogs]

Thanks Lou. I was fiddling with the intake a little last night. So far it looks okay, but I haven't thoroughly checked it yet.

Got called outta' town on business and I have to leave tonight, so the project goes on hold 'til I get back.

 

[HT32BSX115]

I apologize as this is my first time posting onto this website and am struggling to find the correct spot to ask this question. We are in the process of purchasing a 1999 Sea Ray 330 Express Cruiser and reading thru some of the documented repair reports we came across the following:
While checking alignment of port engine assy it was discovered that the extreme misalignment as caused transmission coupler to be erroded @ the bearing face contact point. Machined this face true and checked fit. Properly assembled the fit seems fine and with correct torque applied internal bearing support seems adequate.
After all this --- the report read that rolling resistance seems to be high ........ what could possibly be the issue with the transmission?​

Howdy,

Welcome aboard!

Well, this would be called a "Thread Hijack"

Please have a look at the following thread:

http://forums.iboats.com/forum/engin...ion-for-diyers

There's quite a bit of info there and it may answer some of your questions.

Otherwise, A MOD will probably move your post.

Regards,


Rick


EDIT - Rick is not seeing things. The post has been moved to a new topic - http://forums.iboats.com/forum/gene...718-potential-purchase-repair-report-question GA_B

 

[southkogs]

Well, good news: I finally got to do the compression test and all six cylinders are showing 120 psi. I'm waiting for some parts to come in to some bit piece work and then I'll reassemble everything and see how we're moving water.

 

[Lou C]

Very good on the comp test readings, I think when my boat comes out for the winter I'm going to put in an buzzer warning system for high water temp/low oil pressure. They don't cost much and can really save you. I put in a GPS wired to my VHF and also a gas fume detector last year, so this is the next upgrade, in addition to new gauges....

 

[redneck joe]

good deal, you're missing a great weekend to be on the water...

 

[southkogs]

Had a pretty full schedule this past week and this weekend, so it actually has worked out okay for me. Just enough time to sneak out into the garage for an hour here and an hour there. The weather today, there's a good chance that water is nearly boiling anyway!

Hope y'all had a good time.