Burnt Rubber Smell

[3rdDonzi]

Pulling my girlfriends kid on a kneeboard and when stopped smelled faint burning rubber, lifted hatch and it was definately from my boat but very faint, no smoke or dust from belts. Both belts seem tight, all guages completely normal,
Any ideas????
Thanks,
3D

[Walt. H.]

If you're not over heating and burning your exhaust boots then i'm sorry to say most likely your engine coupler is probably slipping from the extra strain of pulling that wakeboard, and if so the engine has to be removed to replace it because it's bolted to the back of the flywheel.

[Just Say N20]

My Volvo coupler doesn't have any rubber in it.

Props do, but my outdrive slips into a splined hub that is attached to a vibration dampener, clutch plate looking thing.

[Walt. H.]

My Volvo coupler doesn't have any rubber in it.
Props do, but my outdrive slips into a splined hub that is attached to a vibration dampener, clutch plate looking thing.

Bill,
I'm taking for granted it's a Mercruiser or OMC drive which both use a pressed rubber insert hub coupler, which is always the cause when someone states I smell a slight odor of burnt rubber.
Followed by I can only go slow without my engine reving and i'm not going anywhere's, and of course one would have to have a kean sense of smell like a bloodhound to smell a slipping propeller hub submerged in water..

[3rdDonzi]

Yes sir, its a 350 Mag mercruiser with Alpha 1 drive.
Do you suppose its definately shot when you smell burnt rubber or could it be salvaged by alignment and lube? So far its not slipping at all and runs great all the way to top end.
Thanks,
3D

[axelkloehn]

check if one of the belts is hitting the water hoses, sometimes the hose from the pump gets loose and is cut by a belt. Just an idea, I had it once and it really smells like burnt rubber....

[silverghost]

If it is not a slipping or failing belt , or burning exhaust hose it must be your drive coupler.
Make sure that your engine's pullys are not rusted from over the winter and grinding away at your accessory drive belts.

If the coupler is in fact starting to slip It cannot be fixed with lube , allignment, or anything else; and sooner or later will need to be replaced.
That extra towing load may have just been too much for a drive coupler that is just starting to slip & eventually fail.

[mrfixxall]

check your motor mounts.the port side is usually the one in ? it will loosen up and cause a misalignment..if they are loose then you will have to pull the drive and realign everything..btw if they are loose tighten the bottom nut up towards the top one..

[MOP]

If the tab washers were installed properly the lower nut will not move, the upper nut can rise. All to true many have no clue of the sequence when setting up the motor mounts.

[gcarter]

check your motor mounts.the port side is usually the one in ? it will loosen up and cause a misalignment..if they are loose then you will have to pull the drive and realign everything..btw if they are loose tighten the bottom nut up towards the top one..

And add some thin jam nuts to the top.....
The uppers will not loosen again.

[silverghost]

If this was one of your very first boat rides of the new season after a long winter's sleep for your boat you might smell all sorts of things burning off the engine.
Engine Paint
Antifreeze from winterizing
Fogging oil
Engine oil
Hoses
Hydraulic fluid
Drive lube

If this smell persists then you should look into it a bit more.

Make sure your sea water pump's impeller is good and your engine is not over-heating.
Is there a normal amount of exhaust cooling water comming out both exhaust tailpipe tips ?

As long as you do not see any slowing of boat speed VS engine speed your rubber drive coupler might be OK.

When the drive couplers start to fail they tend to go down-hill very fast and you soon find your boat going very slowly after a maximum slow hull speed is attained while your engine's RPMs start to climb very fast. You then really know you have drive coupler slippage.

Let's hope it's just old oil, paint, or fluids burning off your exhaust manifold's hot spots.

Good Luck & keep us posted ~

[LKSD]

Bad Impellers allowing the exhaust rubber boots & hoses to burn or bad couplers starting to fail are the usual leading causes of burnt rubber smells in boats.

Jamie / Lakeside


.

[TBroccoli]

I had the same type of smell last season. It only occurred after a hard run. I trouble shot everything. It turned out to be a bad cap on the gear oil resevoir. Mine sits right above the stbd manifold. A hard run increases oil pressure, which leaked oil through my defective cap and dripped onto the hot manifold. Result = burnt rubber smell. I hope your problem is this simple to fix.