spaghetti seal AND Permatex 51813?

[The red boat]

I’ve read several posts here that say if your power head halves have a spaghetti seal, install the spaghetti seal with 847 sealant to hold it in place but DO NOT also use Permatex 51813 sealants on the flanges and metal mating surfaces.

I also read if you do not have a spaghetti seal, then go ahead and use the 51813 on the metal surfaces.

is this accurate or should I use both (I have the spaghetti seal and a tube of 51813).

just want to make sure I understood the other posts I’ve been reading.

[fleetwin]

Well, I’m not sure what the Permatex 51813 sealer is… I would only use the 847 with the spaghetti seal. The 847 is quick to dry, and strong, and will hold the spaghetti seal in place.
The later model large engines without the spaghetti seal use the OMC gel seal, which is an anerobic sealer, dries in the absence of air. I’m not sure if the permatex 51813 is the equivalent to the gel seal….
Just did a little research, and it looks like the permatex 51813 is the equivalent to the OMC gel seal.

[The red boat]

I agree with what you are saying fleetwin – that’s what I read here.

I was considering using the Permatex 51813 on the mounting surfaces of the crankcase and only using 847 in the groove that holds the spaghetti seal in place – like you say.
Some posts I read on here said if a motor has the spaghettis seal, install that with 847 but do not put any other sealer on the rest of the mounting faces. Other things I’ve read says to do both.

[Bob Wight]

Permatex 51813 is an anaerobic sealer equivalent to the OMC gel seal. As far as approaches, gel seal wasn’t around when these motors were originally assembled so 847 will work in conjunction with the spaghetti seal. Some folks feel that the modern day 847 is messy and starts to cure before the case halves are fully assembled, possibly leading to gaps in the finished joint. So this is why some just use the 847 to hold the spaghetti seal in place, then use the gel seal for the joint faces. There are certainly others with more experience than me (like fleetwin!) who could speak more about this.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1955 Johnson QD-16
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[fleetwin]

Well, the 847 is surely a powerful/strong sealer, but is definitely tough to work with and dries quickly. I wish it came in smaller more controllable tubes.
Theoretically, you are only using the 847 in conjunction with the spaghetti seal to just glue it in place. The spaghetti seal is doing all the sealing, the 847 just holds the spaghetti seal in place. So, I would use as little of the 847 as possible, just enough to secure the spaghetti seal in place. Excess 847 will dry quickly and could shim the crankcase halves apart slightly.
I would not use the gel seal in conjunction with the 847/spaghetti seal. Chances are good that the 847 will get mixed with the gel seal rendering it useless anyway. Once again, the 847 dries quickly, so you don’t want to spend time applying gel seal giving the 847 time to set up before the crankcase halves are assembled and torqued.
The gel seal is nice because it doesn’t not dry/set up until the halves are assembled. But, the downside of the gel seal is the prep. It is tough to tell if you have removed all the old gel seal, because of its light color, the manual recommends using a black light to make sure all of the old gel seal is removed. The crankcase halves must be perfectly clean and dry before applying gel seal, the slightest bit of oily film will render it useless.
So, the benefit of the 847 is that it is forgiving, and will dry/seal no matter what, its downside is its quick dry/set up time.
The gel seal does not dry until the halves are assembled, so you have all the time you need to apply it. It’s downside is the prep, which must be pretty much perfect, or the get seal is useless.
Seeing a crankcase leak after starting a rebuilt engine is a downer for sure, so the importance of sealing the crankcase halves properly can not be over emphasized…

[Author]

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