Johnson 150 Carb Intake Leak

[Philn]

Johnson 150 Carb Intake Leak
Have been experiencing a high idle (among other things).
Ran at idle, sprayed carb cleaner on the port side where throttle body meets the intake.
Idle went down 100-200 rpm.
Same results when spraying next to all three carbs, so intake appears to be leaking all the way down.
Tightened the mounting bolts a little - same results, idle went lower when carb cleaner was sprayed.
Starboard side ok.

Took off the three carbs - Rubber seals (gaskets) between carb and throttle body and between throttle body and intake look good and are fairly new. Throttle body looks very slightly warped after putting a straight edge down the length but I am not too inclined to replace it at $450 a copy.

My question is this:
These gaskets (seals) are thin and flimsy and don't seem to protrude enough to get a decent seal.
First: get a new set of gaskets.
Then put some OMC gasket sealer equivalent like Permatex aviation sealer on both sides of the gaskets to promote a better seal and essentially increase the thickness a little. Install, let dry overnight.

Any input would be appreciated.

 

[bob johnson]

Re: Johnson 150 Carb Intake Leak

id say no to the sealer...id say yes to new gaskets....and proper torque on the bolts.....if no good.... then try your sealing..but id use a sealer like indian head...a thin sticky layer......

good luck

sometimes new parts are needed...cob job repairs don't usually last

bob

 

[Faztbullet]

Re: Johnson 150 Carb Intake Leak

Cross flow or 60 degree??

 

[dwai]

Re: Johnson 150 Carb Intake Leak

what year is the outboard

 

[fishman204]

Re: Johnson 150 Carb Intake Leak

I think a new gasket skimmed with sealer would work.When you reinstall tighten the middle bolts and then top and bottom.Sounds like someone did the opposite befofore

 

[Philn]

Re: Johnson 150 Carb Intake Leak

Motor is 1997 Johnson 150 HP Looper 60 Degree.

 

[bob johnson]

Re: Johnson 150 Carb Intake Leak

manual says DO NOT use sealer on the seal between the manifold and the block. the seal between the manifold and throttle body is a spigetti seal...........neal seals, gaskets and proper torque should help....make sure no threads are stripped bob

 

[dwai]

Re: Johnson 150 Carb Intake Leak

where are you located is it cold also is it coughing at all

 

[Faztbullet]

Re: Johnson 150 Carb Intake Leak

In have seen this on several of these engines. The problem was the core plugs on throttle body was leaking and how I found it was by spraying carb cleaner thru the intermediate jet and low speed passage. It would actually bubble out around core plugs and JB welb fixed em right up. Also the passage cover can leak also..

 

[Philn]

Re: Johnson 150 Carb Intake Leak

Squirted carb cleaner in the topmost opening above idle mixture needle.
Cleaner leaked out of where the fuel manifold mounts into the throttle body.
I assume not good.
I am ordering new manifold orings.

To answer dwai: location: warm SW Florida. No cough when motor runs or dies. No sneeze either.

 

[Faztbullet]

Re: Johnson 150 Carb Intake Leak

You found it....