Got it running, couple questions, VIDEO included

[Gangly]

Note: Video link is attached to bottom.

A better picture (before carb rebuild), by request lol.

I finally got around to rebuilding the Carbs. My father stopped by to help out and it was great fun, havent worked on auto/machines with him in a long time so it brought us down memory lane a little bit. Anyways, finished up the carb, installed everything, and have a few questions. Also, I left the water pump access cover off to check for leaks on teh water pump after installing a new one and Ill put it back on later.

1) I now have fuel leak at the fuel feed line fitting where it attaches to the carb. Am I supposed to use thread tape on the threads for that fitting, is there possibly an o-ring I didnt see that goes in there?
2) The idle is sitting right around 1100 RPM's with the engine temp around 12.5 (X10 C). Is it possible it was still idleing high because it was cold? Do boats do that?
3) I saw water coming from the two pin-holes close to where the muffs attach, is there another "pee-hole" that water should be coming out of that I missed?
4) I had very little water coming from the prop with most of the water coming from the transom area. After looking closely, the prop was filled with mud-dobber nests so I'll need to clean that out. Is there a chance I might have blown a seal or something because the mud-dobber nests closed a large majority of the exhaust coming through the prop? The exhaust manifolds were warm to the touch, not hot, but warm.
5) The secondary diaphram/shaft that came with the Carb kit was about a quarter inch shorter than the OEM one. The rubber seal from the OEM unit was still in good shape so I left it in, but what would the shorter secondary diaphram shaft do if installed?

1990 OMC 350 574APRPWS
with Cobra Outdrive

 

[HT32BSX115]

Re: Got it running, couple questions, VIDEO included

Howdy,

1) I now have fuel leak at the fuel feed line fitting where it attaches to the carb. Am I supposed to use thread tape on the threads for that fitting, is there possibly an o-ring I didnt see that goes in there?

YOU NEED TO FIX THIS (of course!) Look VERY closely at the fitting. If it's an NPT (national Pipe Thread) fitting, YES. use T-tape. Many carburetors are different and use different fittings.

If it's stock, it likely has a steel fuel line from the fuel pump to the carb. If the carb end is a flared fitting, t-tape will not help and should not be used.

2) The idle is sitting right around 1100 RPM's with the engine temp around 12.5 (X10 C). Is it possible it was still idleing high because it was cold? Do boats do that?

Too high. The automatic choke and/or the throttle linkage is/are adjusted wrong. You MUST fix this or you will eventually damage the clutch dogs in the drive. The automatic choke operates independently of the actual engine temp.

3) I saw water coming from the two pin-holes close to where the muffs attach, is there another "pee-hole" that water should be coming out of that I missed?

No

4) I had very little water coming from the prop with most of the water coming from the transom area. After looking closely, the prop was filled with mud-dobber nests so I'll need to clean that out. Is there a chance I might have blown a seal or something because the mud-dobber nests closed a large majority of the exhaust coming through the prop? The exhaust manifolds were warm to the touch, not hot, but warm.

All normal. You should also ensure that you have good water flow from the transom raw water supply hose to the t-stat housing. If there's a power steering or oil cooler installed, ensure that they are free of debris.

5) The secondary diaphram/shaft that came with the Carb kit was about a quarter inch shorter than the OEM one. The rubber seal from the OEM unit was still in good shape so I left it in, but what would the shorter secondary diaphram shaft do if installed?

I cannot say here without seeing the carb "kit" Many carb kits are "generic" They are used for many different carburetors. Some of the parts are not used in all cases.



If you do not have an OMC service manual, you should get one. (Not a Seloc or Clymer etc)

If you haven't changed your drive lubricant, you should. Because it's a Dog-clutch Cobra, you MUST fill it according to the OMC manual. I.E. DO NOT FILL IT FROM THE DRAIN PORT!


Cheers,


Rick

 

[Gangly]

Re: Got it running, couple questions, VIDEO included

Rick,

Thank you for the very informative and helpful response, I appreciate it a lot. I'll lower the idle to around 600 rpms before taking it out to make sure it doesn't tear anything up.

Do these motors idle higher when cold and then settle down or should they be at the recommended idle speed from the moment it start up?

Thanks again for the help and great information, I appreciate it a lot.

 

[HT32BSX115]

Re: Got it running, couple questions, VIDEO included

Do these motors idle higher when cold and then settle down or should they be at the recommended idle speed from the moment it start up?

It depends on where and how the automatic choke is set.

I don't know how yours is set up, Some have a "step" on the linkage that will increase the idle a bit and some have an adjustable "step"..... When the "heater" warms up, it'll "trip off" when you increase the engine speed up a bit and back down.

I actually have found that I don't really need the automatic choke since I only boat in warm weather.

Mine is electric and I just adjusted it completely out of the picture and disconnected it altogether.

I am not recommending that you do that but you should ensure that it and the throttle linkage are adjusted correctly. You'll need an OMC manual to do that if you don't know how to do it (assuming you have a stock carb)

 

[talon8]

Re: Got it running, couple questions, VIDEO included

"YOU NEED TO FIX THIS (of course!) Look VERY closely at the fitting. If it's an NPT (national Pipe Thread) fitting, YES. use T-tape. Many carburetors are different and use different fittings.

If it's stock, it likely has a steel fuel line from the fuel pump to the carb. If the carb end is a flared fitting, t-tape will not help and should not be used."

I agree with the first part, THIS NEEDS TO BE FIXED. However, I would not use thread tape on an NPT fitting when there are small ports such as jets and nozzles downstream that can be plugged. Use a thread compound that is compatible with gasoline. Many industrial companies do not allow thread tape to be used on fuel systems because of experience with plugged kits or nozzels.

 

[HT32BSX115]

Re: Got it running, couple questions, VIDEO included

I agree with the first part, THIS NEEDS TO BE FIXED. However, I would not use thread tape on an NPT fitting when there are small ports such as jets and nozzles downstream that can be plugged. Use a thread compound that is compatible with gasoline. Many industrial companies do not allow thread tape to be used on fuel systems because of experience with plugged kits or nozzels.

You are quite right!!

Thread tape is fine on fuel systems if you don't allow it past the beginning of the threads.

It's very easy to go too far with it. Any good pipe "dope" is as good or better though. AND you're right, some do not want you to use it. I think they prohibit it because you can easily crack a fitting if you over-tighten.......They're probably not as worried about pieces getting into the fuel system......

Including Mercruiser:

From Mercruiser #13, 5A-1

Avoid gasoline fire or explosion. Improper installation
of brass fittings or plugs into fuel filter base
can crack casting and/or cause a fuel leak.
• Apply #592 Loctite Pipe Sealant with Teflon to
threads of brass fitting or plug. DO NOT USE
TEFLON TAPE. [emphasis mine]
• Thread brass fitting or plug into fuel filter base
until finger tight.
• Tighten fitting or plug an additional 1-3/4 to
2-1/4 turns using a wrench. DO NOT
OVER-TIGHTEN.
• Install fuel line. To prevent over-tightening,
hold brass fitting with suitable wrench and
tighten fuel line connectors securely.
• Check for fuel leaks.

 

[bruceb58]

Re: Got it running, couple questions, VIDEO included

Surprised DonS didn't comment when you said to use teflon tape!!

 

[Tail_Gunner]

Re: Got it running, couple questions, VIDEO included

Surprised DonS didn't comment when you said to use teflon tape!!

Give it a moment....probably hasnt had his mourning coffee...eep:

 

[HT32BSX115]

Re: Got it running, couple questions, VIDEO included

Surprised DonS didn't comment when you said to use teflon tape!!

Whew!....Close! I am sure I caught it in time!!!

Although, like different kinds of oil.....I have used it for years on all sorts of NPT fuel fittings and "have never had a problem" but actually, I like the TFE pipe dopes much better.

 

[Gangly]

Re: Got it running, couple questions, VIDEO included

Thanks for the heads up guys, I'll check for the Loctite Pipe Sealnt with teflon.

 

[Silvertip]

Re: Got it running, couple questions, VIDEO included

If the fuel line screws into a separate fitting that also screws into the carb, there is typically a very thin plastic like seal that goes between the fitting and carb housing. That fitting is definitely NOT an NPT thread and using any sealer will not stop a leak there. That's what the seal is for. The pipe will be flared and screws into the adapter just discussed. The flare does the sealing -- not the threads. If the flare is buggered up or you have the thing cross threaded no amount of sealer will stop the leak.

 

[Gangly]

Re: Got it running, couple questions, VIDEO included

There are two fittings for sure. The fuel line is flared metal with a brass fitting, and there is a second brass fitting that is screwed into the carb. The fuel line brass fitting screws into the brass fitting that is already screwed into the carb. I did not see a thin plastic like seal that went between the fitting and carb housing, Ill have to check on that. Thanks for the heads up