OMC 175 BAd overheat, is it all done now?

[Pacific Lots]

I have a 1985 V6 Evinrude 175 that has very low hours on it. I live in Key West and Saturday we ran it into a muck bank that crept up very slowly so I did not realize we were in dirt/mud until we'd been in it a good while. When the boat finally came to a hard aground, the motor had been sucking mud for at least 5 minutes straight. We tilted motor and got free (30 minutes of pushing in ankle deep water) and the engine started, though a bit slower than usual. Went to head away and noticed no cooling. Shut down motor and waited. Started up again and temp gauge still showed hot but as I increased throttle, the temp dropped on gauge but still no water out the whale hole pee indicator. I tried to accelerate to hopefully clear it and boat ran fine until it made that never good noise of a noisy slow to stop dead, getting ever louder as came to a stop. No "broken" noise, just kind of ginding to a halt, like it was angry. At that point, gray smoke appeared out of every small hole on the engine cover. After tow in and overnight cooling (it took hours to cool down) the motor turns free by hand and sounds and feels normal but is dead at the key. I later realized that the wire was off at the temp alarm. Now both heads have darker paint than the rest of the motor but other than a few melted plastic bushings where wire hold downs are, the motor looks okay. However with much discoloration on both heads. In light of the fact that the motor is a 1985, what do you all recommend. Can a motor take this much heat and still be good? Is there a fusible link or something that would have possibly melted or blown that now makes the electrical system to the motor appear dead? It was really hot and seemed to have burned off the 20+ years of oil build up on the case. It was a great runner otherwise, great tilt, elec choke, good lower unit, smooth shift, what do I do now? The saddest part was that I have a great GPS chart plotter and after the fact could see I was running where I should never have been. I can easily upload a photo if anyone thinks it will help

 

[tashasdaddy]

Re: OMC 175 BAd overheat, is it all done now?

there is an inline fuse holder near the starter solenoid. this is the starting circuit. or you can jump the solenoid, with a auto remote switch, to operate the starter, and do a compression check on all 6 cylinders, that is the first test.

this is an 88 90, but should be similar, you can see the fuse holder in the lower right, and the auto remote switch connect to solenoid, one to the large pos post coming into the solenoid, the other to the smaller post next to it. activating the switch is the same as turning the key.

 

[Pacific Lots]

Re: OMC 175 BAd overheat, is it all done now?

Were you thinking you attached a picture of that fusible link on an 88-90? I did not see a link to a photo or any photo otherwise, am I missing something?

 

[tashasdaddy]

Re: OMC 175 BAd overheat, is it all done now?

sorry, crs disease.

 

[Gary H NC]

Re: OMC 175 BAd overheat, is it all done now?

compression test is the first thought. It may be worth pulling the heads and checking everything.Thermostats and a new impeller for sure if the cylinders check out ok.
The fuse should be that smaller red plug on the lower right of the picture.

 

[Pacific Lots]

Re: OMC 175 BAd overheat, is it all done now?

Any idea what the compression should be at each cylinder? Do motors that get this hot usually survive? Does internal damage happen to things like those little roller bearings or is all damage in overheat usually limited to piston, rings, head and gaskets?

 

[tashasdaddy]

Re: OMC 175 BAd overheat, is it all done now?

motors have survived. you will not know until you trouble shoot. turning over is the first good sign.

 

[ezeke]

Re: OMC 175 BAd overheat, is it all done now?

Very often when an engine overheats the cylinder head gaskets are damaged, allowing water to reach the cylinders. Good shop practice requires replacement of the cylinder head gaskets. In the meantime, add extra oil to your cylinders directly until you get this sorted out.

The compression readings should be fairly even, within 10% of each other. That is much more important than the individual readings.

 

[emdsapmgr]

Re: OMC 175 BAd overheat, is it all done now?

A new engine might have 95+ lbs compression. Follow Ezeke's 10% rule. If compression looks ok, then you can get into checking the impeller, head water covers, thermostat housings, etc.

 

[Pacific Lots]

Re: OMC 175 BAd overheat, is it all done now?

Thanks for all your help, I will let you know what I find when I start on Compression Test.

 

[mikesea]

Re: OMC 175 BAd overheat, is it all done now?

Another thing to check.I would take the heads off for a couple reasons. 1)you sucked alot of sand,you may want to remove the water jacket covers and check and clean for sand,also the passages in the block and head passages,2)there are 6 rubber water deflectors inside the block,the heat builup likely collapsed them,they will likely need changing,3)check cyl.walls for scoring 4)head gasket may have issues 5)check the heads for warpage,that is important,especially with that eng which I believe is a big bore.6)If its a big bore,it has been bored about to capacity.When heads are off,pay special attention around the area where the alum.block meshes with the steel cyl.sleeve.Often they delaminate,the salt in Fl.kills those areas add to overheat can lead to probs.Even if you have good comp.if it were my eng.I would do as I said.I had a few of the 2thirstyfives 235's which were overbored v6's and had problems with water seepage where Im talking about the meshing of block and cyl.Im in Islamorada and know a great machinest up here.Send me a Privat message if you need help.I'll give you tel.# of me and shop if you need it.We have a few guys with used parts.Good Luck. Mike

 

[Pacific Lots]

Re: OMC 175 BAd overheat, is it all done now?

So I did the compression test today, the left side when facing the engine from the back of the V6 has compression of 60 pounds per cylinder, give or take 3 pounds, consistently on that side. The right side had 35, 10 and 10, from top to bottom. so I pulled the head on the left side and the bottom two cylinders look great but the top one is a bit scored, but more importantly the piston surface is kind of rough, like tiny bumps on it. The inside of the head on that cylinder is also rough, same as the piston. The head appears fine otherwise and the motor came apart very easily, if you remember it has less than 200 hours on it since new and I know that to be a fact since I have known the owner and the boat since new. so the questions now are what next? Do I have it bored and spend money, remember it is a 1985, or do I throw it away, or do I replace the head gasket and check the compression again on the right side and if okay, change out the impeller and thermostats and try to make it run again? It was a great engine a week ago, great tilt, hydraulic steering, starts at the touch of the key. What would a rebuild to this motor run and who does that stuff in the florida keys? Any answers will be appreciated...

 

[tashasdaddy]

Re: OMC 175 BAd overheat, is it all done now?

suggest calculate the parts probably needed, and your time. compare to replacement, used or new. you can get parts and prices here.

http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

 

[mikesea]

Re: OMC 175 BAd overheat, is it all done now?

I suggest you dont run it with the damage I see.It needs to be rebuilt.What it will take depends on what it looks like after being torn down.You may have cracked ports on the cyl. sleeve(s) they cn be costly.But,probably not.On the good side.You have an 1985 which is the small3.50 bore so pistons are cheaper a bit,the areas I was concerned about look OK.Your choices are,buy a remanufactured powerhead from a rebuilder,The BOAT TRADER has many ,but you need to be educated.PM me about some in FL.IBOATS at one time had some advertised ,but I dont see them anymore.But I may have overlooked them.You can also but the parts off IBOATS. a complete bearing set,gasket set,pistons will be determined on how bad your cylinders are.We see one for sure,but did others get screwed too.Likely the one bad one siezed it up and that may be the only bad one.A good machine shop that does powerheads can help you out on the specs.Again .I have a great machinist in Key Largo.If interested.PM me ,I'll call you or PM you back with info.The guy rebuilds also,.But He is the kind of guy that wont short cut.He will do all 6 cylinders new to next oversize all new piston kits,new everything.But I'll guess at 3800 -4000.Thats usually for complete drop boat off,pick boat up.He's good,not cheap.There are a few budget shops in the Keys,but Id rather do my own work and buy new parts.

 

[emdsapmgr]

Re: OMC 175 BAd overheat, is it all done now?

No point on replacing the head gasket for further testing. The engine won't run with that compression. Severe overheats like this can absolutely crack the liner(s) in the port bridge areas. These need to be inspected. A crossflow our shop is currently working on was severely overheated. 5 of the 6 holes would clean up at .030. The 6th hole was so egg-shaped that it needs a new liner. You need to check the bearings for overheat and pitting/abrasion. I'd follow Mikesea's advice and get the engine to a reputable machine shop for teardown. Once you know the condition of the block, and the rotating (crank/rod) assembly you can decide what you want to do. You should be able to find some reasonably priced crossflow rebuilds.

 

[Pacific Lots]

Re: OMC 175 BAd overheat, is it all done now?

Here;s the rest of the story. The top cylinder seemed to have detonated a bit and wore the sharp edges right off but as I said, the wall is not too badly scored. so I put a new head gasket on it and re-checked the compression. all are within a few percentage except the top right, the one that detonated. But I checked the walls of the cylinder carefully and not much scoring, most damage was to the piston and the resulting metalic spray on the head of that cylinder. I decided I would check to see if it would run and put everything back together and the thing started on the first flick of the key. Any chance the cylinder scoring will smooth out on running it rich and just putting muffs on it and letting it run for a while? It runs and idles fine, did not replace the impeller or the t'stats yet since I didn't want to waste my money on them if it was truly dead but now I think I'll replace the impeller and t'stats and run it on the trailer. Anyone see any great harm in doing so other than a complete blow apart? I don't think an "85" is worth a rebuild when you consider how many repowers there are laying around in the keys for a few grand. Advise me if anyone has an opinion... Otherwise I plan on running it and seeing what happens. Hopefully my day doesn't end in a bang.

 

[Cricket Too]

Re: OMC 175 BAd overheat, is it all done now?

I would replace the t-stats and water pump, complete, not just impeller, and run it in the water. You want to see if it will run with backpressure, and with a load on it.

If it does, then just run it, run it and keep you eyes on the compression. You may get another year out of it, maybe only 2 months, but if you don't want to rebuild then just run it into the ground, the repower.

 

[HybridMX6]

Re: OMC 175 BAd overheat, is it all done now?

If only that top one is bad I'd consider having it checked out to see how bad, as in do you need it bored or just honed. If you don't want to spend a fortune and it's not too bad, just replace the one piston and rings, then re-try the compression test. Similar to what I'm doing right now on a 3cyl.

 

[jay_merrill]

Re: OMC 175 BAd overheat, is it all done now?

What were the compression values after you reinstalled the heads with new gaskets?

 

[Pacific Lots]

Re: OMC 175 BAd overheat, is it all done now?

After replacing the head gasket on the bad side, the compression is 65 pounds give or take a few pounds in every cylinder except the one that detonated. That cylinder is at 30 pounds.

Anyone know what it would cost to have a shop hone one cylinder and replace the rings as well on just one. How hard is it for me to do, can you spin the honing tool in a drill? How hard is it to get to the connecting rod and remove one piston to do so, how do you keep grit from entering the reed valves on this cylinder while honing?