Electrical or burnt rubber smell

[TBroccoli]

I get a burnt rubber smell once I slow down from a 45-50mph run. It was mentioned that it could be my exhaust hoses breaking down from the inside out. Is it normal to be able to squeeze an exhaust hose by hand? I can actually squeeze some flex into my hoses. How hard is it to replace the hoses? I have silent choice.

[mrfixxall]

I get a burnt rubber smell once I slow down from a 45-50mph run. It was mentioned that it could be my exhaust hoses breaking down from the inside out. Is it normal to be able to squeeze an exhaust hose by hand? I can actually squeeze some flex into my hoses. How hard is it to replace the hoses? I have silent choice.

Loose assory belt? is the boat steaming to?

[smokediver]

engine coupler ?

[Mr X]

engine coupler ?
No doubt.

[TBroccoli]

MRFIXALL: I noticed for the first time a little steam out of my starbord exhaust this weekend. It went away after idling for about a minute.

[TBroccoli]

How do I check to see if its the engine coupler? If it was the coupler wouldent I get the smell all the time? I can be tubing for an hour running around 25mph and get no smell.

[mrfixxall]

How do I check to see if its the engine coupler? If it was the coupler wouldent I get the smell all the time? I can be tubing for an hour running around 25mph and get no smell.

their would be tiny pieces of rubber around the inside of the gimbal area where the drive input shaft goes through,,also you would be down mph..

[MOP]

Ok when was the last water pump job? How hot are the risers after 10-15 minutes running on plane, they are usually uncomfortably hot but you can still hold your hand on them. If they are cooking hot there could be two things, plugged risers or the pump is going bad.
To change the hoses the easiest is to get new riser gaskets and pull the risers to replace the hoses.
If the coupler is starting to go like Mr. Fix said there is lose rubber at the back of the hub maybe some in the bilge, if you are tubing without slippage it may be just fine.

You can check your water pump flow by disconnecting the hose coming from the transom at the Tstat housing, put it in a bucket and start the engine let it run for a full 60 seconds. You should have close to a gallon of water at idle.

Phil

[GeneD]

Fan belts don't always squeal when they slip...
Check for rubber powder at the front of the engine.
If there is, buy new belts at your local auto parts store. Bring your old ones so they can match 'em up. Tell them you want the best they carry...
Your belt problem (if one exists) should be cured...

[slapshot11]

This happened to me last year at the Dust Off. Turned out to be a pin hole leak in the water pump housing which was shooting water onto the belt causing it to slip, burn and smell.

[TBroccoli]

GeneD: Thanks, I will replace the belts. Thats easy and it can't hurt. They haven't been changed in a while.

MOP: Thanks, I replaced the raw water pump and housing last sept. I think I got all impeller pieces out. I seem to have good water flow now. I will have to check the riser temp this weekend. They were replaced in 2003 and have seen no salt.

I have two hoses coming off the risers. The first goes to the tee for the silent choice. then another from the tee to the exhaust tips. Is it easier to remove the exhaust tips or the risers?

I will also look for engine coupler chunks.

[TBroccoli]

As of now I am ruling out the engine coupler. I found no rubber pieces and the boat still runs strong. I am replacing the belts this weekend and will report back later.

Thanks for the help.

[TBroccoli]

Replaced the belts. Still getting the burnt smell.

MOP: Ran the boat for a while, got the smell again. The starboard riser and manifold are hotter then the port. The water out of the exhaust is hotter from the starboard side. I get good water flow from both pipes while at idle and even at about 2000 rpms. Could the burn smell be coming from a missed piece of impeller that was changed out the end of last season? I thought I got it all. Is there any flushing I could do?

[MOP]

There are always slight distribution differences but have the intake restricted would affect both sides, I am back to pull the risers. I am assuming you are running iron manifolds, they many times will have junk flake off. It does not always mean they are shot but in need of a cleaning.

[GeneD]

Well, this is a bit of a puzzlement isn't it?
Hopefully, you tightened up the belts good. My partner says they should 'sing' when thumped.
Did you find any rubber powder across the front of the engine? If so, did you hose it off?
The cooling problem...try this...
Remove the hoses going from the therm housing to the manifold and riser. Put city water pressure to it and see if you get a good flush thru. Like MOP says, rust will flake and get caught in the passages. City water pressure can flush it out.
And if you got them, look at the check balls. I'm personally done with check balls and have removed that whole system from my engine. Blocked off the riser and removed and blocked off the 't'. Now everything has to go thru the manifold and up and out of the riser. Merc figured it out years ago and removed that element from the newer engines.
You may eventually have to remove the risers for peace of mind.
But the smell...there is no doubting that it could be your exhaust hose melting...but if you've got good water flow...how can this be the source?

[MOP]

You should have about 1/2 to 3/4 sag in the belts when you push on them any tighter and you kill the bearings in the accessories.

[TBroccoli]

Could the smell be coming from a missed piece of impeller? How ridgid are the exhaust hoses? I can squeeze them a little with my fingers. Some people tell me thats normal some say its not.

[MOP]

You may have two issues! One the hot riser which will give you grief even if it is not the NOW problem, gaskets are cheap that is where I would start. When you remove the risers you will be able to see if the hoses are starting to burn inside.

Phil

[TBroccoli]

I removed the hose from the therm to the manifold and flushed it out. It was clean. I then flushed into the manifold and it flowed ok. I then removed the water flow and the water back flowed out of the bottom of the manifold. It all looked clean. The manifold and the riser both have what looks to be a 3/4" plug in each. The one on the manifold is on top and the one on the riser is on the front. Can I remove them and flush through them?

[MOP]

The problem is the flakes of rust get caught in the narrow slots going into the riser, they can flow fairly decent and still have a problem at cruise and above if there is blockage. One being on the hot side tells me clean it!

[TBroccoli]

I gave up and took the boat to the shop. The tech called today and said he ran the boat for about 30 minutes in a tank and the water temp from each exhaust was 117 and 118F. He was going to pull the risers and check condition and look at oil cooler inlet. I told him I flushed the hot side from the therm thru the manifold. Maybe I dislodged something???

[TBroccoli]

Manifold and riser is clear. I have a pulsing hose going into the raw water pump. I will check the impeller.