Is my exhaust too clean?

I just got a '69 Mercury 75 7.5 HP motor. I removed the lower end to install a new water pump and check and reseal the gear box. I find zero carbon build up. I think I have figured out the exhaust pathway, but that pathway is clean enough to eat off of. This should have over 40 years of build up!! All I see is nice clean and dry paint. WTH! Am I looking wrongly at this? Even if the previous owner ran straight gas it should have some build up on it.
Comments would be nice. I have no idea when this ran last. Under the cowl it looks brand new. The guts in the gearbox look brand new. I did a compression test and came up with 63/65, that should go up after I start it up. Bob

Re: Is my exhaust too clean?

bob1340 said:

I just got a '69 Mercury 75 7.5 HP motor. I removed the lower end to install a new water pump and check and reseal the gear box. I find zero carbon build up. I think I have figured out the exhaust pathway, but that pathway is clean enough to eat off of. This should have over 40 years of build up!! All I see is nice clean and dry paint. WTH! Am I looking wrongly at this? Even if the previous owner ran straight gas it should have some build up on it.
Comments would be nice. I have no idea when this ran last. Under the cowl it looks brand new. The guts in the gearbox look brand new. I did a compression test and came up with 63/65, that should go up after I start it up. Bob

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BTT for some ideas on this.

Re: Is my exhaust too clean?

Maybe you found one of those gems that has been put away for years with little running time on it.

I reckon the condition of the driveshaft splines (wear, etc) and the general appearance of the driveshaft (rusty/pitted or like new?) will tell a lot about how it was treated. Apparently never run in salt or it'd be pretty nasty by now.

Hopefully it'll run as good as it looks!

Re: Is my exhaust too clean?

emckelvy said:

Maybe you found one of those gems that has been put away for years with little running time on it.

I reckon the condition of the driveshaft splines (wear, etc) and the general appearance of the driveshaft (rusty/pitted or like new?) will tell a lot about how it was treated. Apparently never run in salt or it'd be pretty nasty by now.

Hopefully it'll run as good as it looks!

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Yep, gears, bearings, shafts all look brand new. The paint inside the cowl/powerhead is like brand new, shiny. The outside of the cowl is beat to hell as whoever owned it let it bounce around in the bed of a pickup. I got the motor and a Ted Williams Gamefisher 12' fiberglass boat for $175.00. Might be a good buy.

Re: Is my exhaust too clean?

bob1340 said:

The outside of the cowl is beat to hell as whoever owned it let it bounce around in the bed of a pickup.

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You might check on eBay, I've seen some pretty nice covers on there lately.

Re: Is my exhaust too clean?

emckelvy said:

You might check on eBay, I've seen some pretty nice covers on there lately.

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Not damaged, just scuffed up. It is a aluminum cover and can be sanded smooth again. I'll re-paint and put new decals on it.

It's a funny motor. The outside is beat up from bouncing in the bed of a truck, and the guts look new. I'll try and do some pictures in he next couple days.

Re: Is my exhaust too clean?

I recently picked up a 79' 90hp and thought the exact same thing about my exhaust. I had the lower unit off replacing the pump and decided to look up the leg. Clean as a whistle. I also was dumbfounded by the immaculate paint job still shinny and new on the block itself. I think that both you and I just found those motors that people did not use much. If you think about it, a guy buys a boat and motor, spends 10 or so grand on it, uses it a lot the first year, gets tired of it, gets to busy for it, and cant bring himself to take a big loss on selling it, so it just sits there, or in your case just rides in the back of the truck.

The bad thing about a motor that does not get used is that there are different things that go wrong than one that is used a bunch. I think I am dealing with some seal issues with mine because they probably sat so long unused and have dried up and cracked. But those issues are a lot better than bad power heads. Consider yourself blessed.