Leaking RPT manifold.

[Brandonium]

A few questions..

It appears that I have a leaking manifold gasket. When I spray carb/starting fluid on the middle valley passenger side. I get about a 200 rpm jump from this area. I've just ordered many parts to tackle this job but I have a few questions.

1). I know the bolt size and thread count for the manifold but I need to know the different lengths of these bolts. I am wanting to swap out to allen bolts but I need to have these on hand prior to me removing the intake. Cannot seem to find anyone who can provide this info.

2). Is it worth removing and resealing each vacuum port that is blocked off with a 3/8 threaded insert? I figure if I am going through everything I might as well check these out as well?

3). I plan to spray the intake gasket with copper sealant. Anything else I need to add especially around the water jackets?

4). Anything else I need to look at or that I am forgetting?

I am planning on replacing the valley pan gasket as well as valve cover gaskets since I will be performing other work on the engine as well. I've attached a picture of the area that is appears to be leaking from.

 

[1975IH200]

1. Did you do a search? I have posted the answer to this question a few times in the past. You can also look it up in the parts manual. You do have a parts manual don't you? Use sealant on the threads as they are exposed either to the water jacket or to intake vacuum, and you don't want another leak.

Qty. 8 each 3/8 nc x 1" bolt
qty. 4 each 3/8 nc x 1 1/4" bolt
qty. 4 each 3/8 nc x 1 1/2 " bolt
qty. 16 each 3/8 flat washer

2. Yes, that is fine, use sealant on the threads as they are exposed to either the water jacket or to intake vacuum, and you don't want another leak.

3. I use copper spray-a-gasket, and torque per the service manual. You do have a service manual don't you?

4. Parts manual & service manual.

 

[Brandonium]

1. Did you do a search? I have posted the answer to this question a few times in the past. You can also look it up in the parts manual. You do have a parts manual don't you? Use sealant on the threads as they are exposed either to the water jacket or to intake vacuum, and you don't want another leak.

Qty. 8 each 3/8 nc x 1" bolt
qty. 4 each 3/8 nc x 1 1/4" bolt
qty. 4 each 3/8 nc x 1 1/2 " bolt
qty. 16 each 3/8 flat washer

2. Yes, that is fine, use sealant on the threads as they are exposed to either the water jacket or to intake vacuum, and you don't want another leak.

3. I use copper spray-a-gasket, and torque per the service manual. You do have a service manual don't you?

4. Parts manual & service manual.

I plan on getting both. I did search both here and bp but never came across anything in regards to length, just thread count. I typically don't have time to work on it so I have rely on shops.. This of course is the last time since I'm burned every time. So I'm stocking up on tools, getting the parts I need to do this job and will invest on the manuals once payday comes back around.

any particular brand that you prefer on the threads that are exposed to water/air? Per posts that I have seen permatex #2 or hylomar seem to be popular for putting on threads but iirc it's not the same for npt threads?

Thanks a ton for the measurements. Just trying to get the vehicle to a place where it's not consistent guesswork on what was done.

I've got the torque specs, those were easy to find on search.

It's the aluminum manifold so I should warm then follow up with another re-torque? Back off slightly then back?

Thanks again for fishing that info for me.

 

[1975IH200]

Either sealant should be fine, just don't use too much. I use a permatex product, I forget the number but it is white in color.

Re-torque shouldn't be needed, but if you want to, after a few heat & cool cycles, and after the engine is back down to ambient temperature, you could put the torque wrench on the bolts in the torque pattern at full torque. do not Loosen and re-tighten the bolts.