Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Sounds like they are in the reman business, which is a little different then just your standard machine shop. I would go for their off the shelf reman's. No waiting. No SURPRISE your's are cracked!!! Or need new valves, springs, and guides.

Just as long as they can match the combustion chamber size to what you're pulling off, which should be no problem considering the heads you have now are truck heads that are as common as belly buttons, you should be good.

I hear ya loud and clear. Thats what I intend to do since the price is so reasonable.

On another note, I finally got around to pumping the oil out of the motor and I cannot see any water in it. Too be perfectly honest though, Im not exactly sure what to look for. I pumped the old oil into a clear container and there is nothing but a perfectly smooth black surface to the top of the oil in that container. Should I be looking for a clearly visible line of water on top where it has separated from the oil? Should I be looking for a milky discolored separation?

Thanks.

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

I hear ya loud and clear. Thats what I intend to do since the price is so reasonable.

On another note, I finally got around to pumping the oil out of the motor and I cannot see any water in it. Too be perfectly honest though, Im not exactly sure what to look for. I pumped the old oil into a clear container and there is nothing but a perfectly smooth black surface to the top of the oil in that container. Should I be looking for a clearly visible line of water on top where it has separated from the oil? Should I be looking for a milky discolored separation?

Thanks.

A little of both depending on how long it's been sitting. If it has been run with water in the oil, it'll be emulsified. If not, there'll be a distinct line (oil floats on top of water)

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

A little of both depending on how long it's been sitting. If it has been run with water in the oil, it'll be emulsified. If not, there'll be a distinct line (oil floats on top of water)

Well it has been sitting for several hours and just looks like good used oil. My plan now was to refill with oil, put the exhaust back together and then run her for an hour on the muffs. Then pull that oil out and check again for water. Is this a waste of money and should I instead spend the money on a compression test tool before putting new oil in and running her?

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Put her back together and refilled the oil and new filter. It took a good while to get her started but after spraying some starting fluid she started up and ran fine. After a few minutes she did get hot though. 180F which according to the manual is overheating. I did put a new thermostat in when I had the exhaust off but I dont know if she is just not getting enough water pressure from my hose as we run off a well on my property and the pressure isnt so great when I have to run a hose out to the end of the drive way. I'm going to pull the water temp sending unit and clean it up. I do have a laser thermometer gun that I was firing all over the block when the gauge was showing 180F. I was able to fire it right at the sending unit and it read at 165F.

There was some very faint white smoke coming out of the exhaust. Not sure what that means.

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

The best test will be to put it in the water and run it up on a plane at 3/4 throttle or so.....

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

The best test will be to put it in the water and run it up on a plane at 3/4 throttle or so.....

I hear ya. After the thermostat replacement and the temps still hanging high I am beginning to wonder about the condition of the impeller. I mean, what else is there? Could the inside of the block be so rusted out that water cannot flow through it properly? I'll take her out on Monday and see how she does.

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

I hear ya. After the thermostat replacement and the temps still hanging high I am beginning to wonder about the condition of the impeller. I mean, what else is there? Could the inside of the block be so rusted out that water cannot flow through it properly? I'll take her out on Monday and see how she does.

Well, most of us usually suspect the impeller first. If the block and heads are really old they can be pretty clogged up with rust. It's all cast iron. It's usually not that much of a problem with a freshwater (not used in salt).

You already replaced the manifolds and risers. so they're clear......

Check the gage if you haven't already. more than one temp gage has lied before!

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Well, most of us usually suspect the impeller first. If the block and heads are really old they can be pretty clogged up with rust. It's all cast iron. It's usually not that much of a problem with a freshwater (not used in salt).

You already replaced the manifolds and risers. so they're clear......

Check the gage if you haven't already. more than one temp gage has lied before!

Ill check the gauge this weekend. I found a tutorial on how to test all aspects of it. Check out the video I made of the stern drive running while on a hose. Does the amount of water coming out around the base of the upper gear case housing and out of the prop exhaust look normal?

http://www.youtube.com/watch?v=r3PXqjS3tfg

 

[bruceb58]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Hard to tell how much water you are getting. You really may need to get the thing in the water to really determine if you have a problem or not.

I would also double check what you are getting on your gauge with an IR thermometer.

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Hard to tell how much water you are getting. You really may need to get the thing in the water to really determine if you have a problem or not.

I would also double check what you are getting on your gauge with an IR thermometer.

Thanks bruce. I do plan to take her on the lake this coming Monday to see how she runs. I do have an IR thermometer and the highest temp I saw at the water temp sending unit was 165.

I want to change the gear oil in the drive before I go out but I have a couple questions. From what I have read, I have to use Type C gear oil in the lower unit only if I have an electric shift. Excuse my ignorance, but how can I tell if I have an electric shift? If I do not have an electric shift, can I use 80w90 in the lower like I can in the upper and intermediate? I am currently doing the research on the proper procedure for draining and filling the units so I should be good to go there once I get the gear oil type question out of the way. Thanks again.

*Edit* Found this write up on how exactly to replace the gear oil in a Stringer drive. Would you concur with this procedure? http://www.marineengine.com/boat-fo...to-properly-fill-a-1985-omc-stringer-with-oil

 

[bruceb58]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

You do not have an electric shift.

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Last week I drained the oil from all three gear cases. The oil in the upper was very milky so I decided to fab together a pressure tester. Got around to testing it yesterday and found that the upper does have a decent seal leak. For now, Im just going to fill it back up with fresh oil and new nylon and rubber washers. I dont want to dump the money and time into resealing the whole gear case now until I can test out whether or not by engine block crack extends into the cylinder wall.

Im headed to the lake tomorrow morning for a quick run around close to shore then Ill take her home and drain the oil and look for water. If there isnt any water in the oil once again Ill consider her okay for light use until I can save up the coin to replace the block.

Also, going back to my temperature issue. Ran the boat on the muffs again and the gauge shoots up to 180F after a few minutes. External temperature, measured with infra-red thermometer at the sending unit never gets above 153F at idle and hovers right around 160F when I rev her up a little. I grounded out the wire from the sending unit and it pegs the gauge so if what I have read around the net is correct that means the sending unit is bad.

Here is a picture of it:

The OMC part number 171690 and from what I can tell, the correct Sierra part is TS26621 3/8". See the link: http://www.iboats.com/Engine-Temper...3515160--session_id.469191005--view_id.392180

That's it for now. Wish me luck on the lake tomorrow!

 

[HT32BSX115]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

I grounded out the wire from the sending unit and it pegs the gauge so if what I have read around the net is correct that means the sending unit is bad.

Not quite correct. Grounding the sending unit just pegs the gage and tells you that the gage is good.

Go invest in an inexpensive multi-meter from Radio Shack or Harbor Freight etc...

The resistance values for many senders are in the following PDF.

faria-instruments.com/site_manuals/IS0085E.pdf

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Not quite correct. Grounding the sending unit just pegs the gage and tells you that the gage is good.

Go invest in an inexpensive multi-meter from Radio Shack or Harbor Freight etc...

The resistance values for many senders are in the following PDF.

faria-instruments.com/site_manuals/IS0085E.pdf

Thanks for the link HT. Ill check the resistance when I have her running on the lake.

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Took the boat out to the lake this morning. Ran her around for a good 20-30 minutes getting her up to WOT. She ran as perfectly as she ever has. When I got home I pumped out the engine oil and found absolutely no signs of water in it. There is a smell of gas however. Ill have to look into what that means.

So, did I dodge a major bullet with the no water in the oil thing? Obviously the block still needs to be replaced, but would it be a reasonable assumption to say I could use the boat for the remainder of the season if I baby her? I guess its really just a ticking time bomb so I dont really know where to go from here.

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Thought of something else I had a question about. Totally unrelated to the other issues with my boat. I recently found the grease fitting for the steering actuator. I've never greased it in the 3+ years Ive had the boat. I have some marine grease in my grease gun and I figured I would grease it up. Is this the correct grease to use? What do you all recommend? How many pumps from the grease gun does it need? I don't want to over do it and over pressure or blow out any seals or anything like that. Thanks.

 

[Nivekt]

Re: Cracked starboard exhaust manifold ('79 OMC 260)(PICS)

Just a bump for some insight into my last two posts/questions. Thanks.

 

[ronb172]

I've been following this post closely. Very good info on here. As far as your last question, I'm damn sure no expert, but I pumped enough grease into it until I saw new grease coming out at the other end. I have a '79 boat with a Ford 351 and OMC 800 out drive. I have new exhaust manifolds on the way now as the previous owner didn't get anti freeze into the manifold at one time.

 

[ronb172]

Well ****, I see this is from 2012. Guess I need to pay more attention.....lol