Burning Rubber Smell and White Smoke from Engine?

[Prince2e]

I recently purchased a Four Winns 210 Horizon with a 5.0 EFI. I’ve been working on it and i’ve noticed there is a burning rubber smell in the engine area. Never thought much of it. Today, I replaced the gimbal bearing, bellows, aligned everything perfectly. Go out on the water and everything is great. 5 mins into the ride, I start seeing white smoke from the engine area. I lift the engine cover and ride for a few minutes and couldn’t see the smoke location. What could these be? The engine never overheated. I checked the coupler by putting it in drive. The prop locks in place like it should and not rubber pieces anywhere. I also noticed water leaking from hoses connected to the risers, and i’m sure the manifolds are bad too. lol

 

[Scott Danforth]

You are most likely overheating and burning up your motor


When was the last time you serviced the raw water pump?

 

[Prince2e]

You are most likely overheating and burning up your motor


When was the last time you serviced the raw water pump?

A few days ago. Temp gauge reads good. Adequate water flow through exhaust

 

[Scott Danforth]

check the temp of the exhaust manifolds with an IR gun.

burning rubber smell and smoke is usually a fire somewhere.

 

[Don't Panic!]

How do the belts look?

 

[Lou C]

Sounds like your exhaust mat be overheating if those manifolds & elbows are original they might be way past their expiration date (clogged by rust, not cooling & overheating the rubber exhaust hoses). Water cooled exhaust on an inboard has to be maintained unlike automotive exhaust.
Get an IR temp gun & check the temps of the exhaust with the boat in the water. Normal is 100-110 at idle and 135-140 after coming off plane. If higher like 169-180 you have a problem.
Disconnect the hoses that go from the thermostat housing to the manifolds at the manifolds. With the boat in the water start it briefly and watch for equal flow from both hoses. If the flow is equal then the exhaust has to come apart for inspection or replacement. It could be clogged on one side so all the water goes to the other & the total flow might look good but it could be very hot on one side.

 

[Prince2e]

Sounds like your exhaust mat be overheating if those manifolds & elbows are original they might be way past their expiration date (clogged by rust, not cooling & overheating the rubber exhaust hoses). Water cooled exhaust on an inboard has to be maintained unlike automotive exhaust.
Get an IR temp gun & check the temps of the exhaust with the boat in the water. Normal is 100-110 at idle and 135-140 after coming off plane. If higher like 169-180 you have a problem.
Disconnect the hoses that go from the thermostat housing to the manifolds at the manifolds. With the boat in the water start it briefly and watch for equal flow from both hoses. If the flow is equal then the exhaust has to come apart for inspection or replacement. It could be clogged on one side so all the water goes to the other & the total flow might look good but it could be very hot on one side.

The issue ended up being a alternator belt that was slipping and worn. Replaced and adjusted and that smell is completely gone!

 

[Prince2e]

Sounds like your exhaust mat be overheating if those manifolds & elbows are original they might be way past their expiration date (clogged by rust, not cooling & overheating the rubber exhaust hoses). Water cooled exhaust on an inboard has to be maintained unlike automotive exhaust.
Get an IR temp gun & check the temps of the exhaust with the boat in the water. Normal is 100-110 at idle and 135-140 after coming off plane. If higher like 169-180 you have a problem.
Disconnect the hoses that go from the thermostat housing to the manifolds at the manifolds. With the boat in the water start it briefly and watch for equal flow from both hoses. If the flow is equal then the exhaust has to come apart for inspection or replacement. It could be clogged on one side so all the water goes to the other & the total flow might look good but it could be very hot on one side.

I did replace the manifolds and the risers were fine.

 

[Lou C]

Glad it was a simple solution!