Exhaust in tell tale 8hp Johnson 2000

Drowned Rat

Drowned Rat

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Hi guys. This is a 2000 model 8hp Johnson. Water in tell tale was intermitant so I changed the water pump impeller, but it's still intermitant. The engine overheats quickly and there is exhaust coming out the tell tale hole. This was a salt water motor. Could this be a cracked block or blown head gasket? Maybe the salt has eaten through the water jackets? Any ideas would be a great help. Thanks!
 
iwombat

iwombat

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Re: Exhaust in tell tale 8hp Johnson 2000

Probably a blown head or exhaust gasket. Time for a compression check.
 
Drowned Rat

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Re: Exhaust in tell tale 8hp Johnson 2000

I checked compression and its just better than 80 on each. Ideas?
 
iwombat

iwombat

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Re: Exhaust in tell tale 8hp Johnson 2000

Compression is certainly on the low side. I'd be pulling the head and giving it a look.

An overheat will certainly cause a head to warp and blow a gasket. You need to find out why it overheated in the first place though.
 
Drowned Rat

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Re: Exhaust in tell tale 8hp Johnson 2000

I've pulled the head and from a purely visual inspection, all looks okay. I think it's odd that both cylinders are about 80 psi. I would expect them to have more variation if it were a blown gasket or warped head right?? Why would the tell tale be intermitant? And how would exhaust gas get into the tell tale? Puzzled.
 
iwombat

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Re: Exhaust in tell tale 8hp Johnson 2000

Okay, well that's the good news then. The other likely suspect for low compression and exhaust intrusion is the exhaust gasket.

As long as we're on the subject, how did you determine exhaust gas is leaking out the tell-tale?
 
Drowned Rat

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Re: Exhaust in tell tale 8hp Johnson 2000

What is the exhaust gasket? You can see the exhaust coming out the hole and the tubing gets VERY hot. Thanks for the help.
 
iwombat

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Re: Exhaust in tell tale 8hp Johnson 2000

So I'm assuming this is a two-stroke 8hp. If not, you never saw this posting.
The exhaust cover is on the (I think) starboard side of the powerhead. It's the other likely cause of exhaust gasses intruding into the water jacket.

However, hot tell-tale and intermittent stream could just be water boiling inside the water jackets. Did you see any oily residue come out? If not, you've just got a cooling issue.
 
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