Ultra Black RTV. Is this going to work?

[ballchinny]

I am a pro wrench, but I got in a pinch on my own stuff. Not happy but.....basically had a small generator needed a valve adjust. On this one, it is a serious PITA, but it got to a point of no hot restart, and I needed it 'right now'. So I made the time to do the job, of course the gasket was toast, I didn't have one, and cleaned the surfaces and did the old RTV deal. Of course not over applied as that stuff can kill an engine, but I did apply to the small cover and let it go to tack free. It's hot and humid. Probably installed cover 20min after the goo application, probably another 15min to get that cover down in there, lightly snugged the bolts and waited as long as I could. Maybe another 15min. Then pulled the bolts down, and did a quick test start 15min after that. So no more than an hour between the goo and first start.

I then waited as long as I could but needed that generator 3hr later. Obviously seeing is believing but it;s currently running and I hate the thought of doing all of that again just due to the rush. I have gray but couldn't find it.

Anyone pushed the time window with success?

 

[The Critic]

The two surfaces should always be mated immediately -- refer to the included instructions. Allowing RTV to skin over before bolting up is a myth. The RTV needs to bond to both surfaces or else it becomes a "wedge."

 

[Chris142]

I would have preferred it cure longer. Like24 hrs

 

[AKhan87]

I use Toyota FIPG (RTV) and you can start pour oil and start using the mated surface in 2 hours if you are in a complete rush, though 15-16 hours is suggested on the tube.

for Permatex Black RTV, it is always 24 hours, they can leak if in a rush.

Also, there is a product called "the right stuff" which heals much quicker, you can possibly use that in a pinch but I personally don't have any experience in using it.

 

[ballchinny]

Yeah, I prob should have just hacked out a gasket. I really hate RTV. Most anything I do either has a gasket or anaerobic sealer on precision surfaces. I buy some of this stuff and it goes bad before I really use much. Obviously I don't put many old V8s together....lol I've always hated that intake setup. Me love Orings.

 

[dnewton3]

Not an optimal application, but probably will work fine.

Many, many years ago, I had an old Honda XR250 dirt bike. The engine clutch side cover had to be removed in the field and the gasket was not in stock at the time at any dealer nearby. So I went to the local Napa and got some blue Permatex RTV. Spread it on and let it set cure for about 20 minutes with the parts mated up loosely. Then I snuged it down and filled it with oil and rode for about 6 hours that day. And the next day. And next weekend ... It never leaked a drop in the next two years until I sold it.

 

[PontiacHO]

In situations where commission based technicians are making repairs RTV is applied, the work is reassembled and out the door it goes. You’re fine.

 

[burbguy82]

RTV is great. I prefer a gasket on some things and RTV on others.. Durability, IMO is more having to do with the prep of the site. Good prep, good result

 

[D60]

In situations where commission based technicians are making repairs RTV is applied, the work is reassembled and out the door it goes. You’re fine.

Rarely with Ultra Black. Ideally, never with Ultra Black

I actually think it's a great product but I've had diff covers leak when I got impatient. This was ~20 years ago and now I'm paranoid -- it cures overnight minimum or I use Right Stuff.

 

[Sumboodie]

I've never waited more than it took me to do the job. Didn't even know that a 24hr cure was a thing until recently.
Been using RTV 25+ years.

Did have a diff cover not seal well once, but I think oil dripped on the RTV before bolting the cover.

 

[burbguy82]

I use Right Stuff.

Me too. Most just refer to sealant as "RTV".

"Right Stuff" is serious stuff. If I remember right, it is the non OEM equal to the same stuff used on duramax lower oil pans. Its consistancy is more "granular" perhaps than typical RTV.

Either way, that is what I predominately use aswell.

I have used it for the lower dmax oil pan, and for the infamous valley leak on the toyota 3urfe engine, and countless other things, never with a leak.

It is expensive though