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Old 01-12-2011, 04:51 PM   #1 (permalink)
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Default Intake Manifold Leak?

This one is probably for Michael but anybody please chime in. 74 Scout II 345, 727, D20, D30F, D44R. Just installed the Holley 0-7448 carb and EGR delete plate. I was adjusting the idle and noticed when I was hand throttling the carb I could see exhaust coming out from under the intake manifold. When I reached under there I could feel a hole right below where the EGR plate is. I could feel a vacuum while it was running and exhaust smoke when throttled. Any ideas? Thanks, Danny
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Old 01-12-2011, 05:38 PM   #2 (permalink)
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Default Re: Intake Manifold Leak?

ok this is an easy one. first off you gotta yank the intake, i know you didnt want to hear that but its inevitable here. there are welch plugs on the bottom of the intake where they casted it. and guess what the one for the egr and choke heater is leaking. well rusted out.
after removing the intake, flip it over. removing them can be done 2 ways. drill and pull with a dent puller or drill big enuff to get a small screwdriver in there and pry out. the second way is not really recomended, but you gotta do what you gotta do. if you look back thru the gas engine sub forum you'll find a post on welch plugs . it tells you the correct size and what to do.
you can get these plugs at any good parts store. dorman makes them. after you replace, make sure you use the copper gasket spray on both sides of your new intake gaskets and nothin else. no RTV anywhere on these motors!!!!. this repair is common and easy! if ya need anything else just ask!!
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Old 01-12-2011, 05:48 PM   #3 (permalink)
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Default Re: Intake Manifold Leak?

Thanks Towpainter3; I'll pull the intake when the weather breaks here. Sounds easy enough and I just happen to have a can of copper spray gasket.
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Old 01-12-2011, 05:53 PM   #4 (permalink)
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Default Re: Intake Manifold Leak?

Quote:
Originally Posted by Danny Phillips View Post
This one is probably for Michael but anybody please chime in. 74 Scout II 345, 727, D20, D30F, D44R. Just installed the Holley 0-7448 carb and EGR delete plate. I was adjusting the idle and noticed when I was hand throttling the carb I could see exhaust coming out from under the intake manifold. When I reached under there I could feel a hole right below where the EGR plate is. I could feel a vacuum while it was running and exhaust smoke when throttled. Any ideas? Thanks, Danny
Yes, that is a VERY common vacuum leak point, actually on BOTH sides.

Pull the intake manifold, replace ALL the welch plugs you see in the bottom, (between two and five), and re-install using NEW gaskets treated with Copper Spray-a-Gasket.
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Old 01-12-2011, 05:58 PM   #5 (permalink)
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Default Re: Intake Manifold Leak?

I take it this would be a good time to install the LPG intake gaskets as well.
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Old 01-12-2011, 06:08 PM   #6 (permalink)
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Default Re: Intake Manifold Leak?

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Originally Posted by Danny Phillips View Post
I take it this would be a good time to install the LPG intake gaskets as well.
Certainly....IF you can find 'em!

I'm still looking for a supplier for the 345/392 gaskets right now.
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Old 01-13-2011, 07:57 AM   #7 (permalink)
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Default Re: Intake Manifold Leak?

Quote:
Originally Posted by Danny Phillips View Post
I take it this would be a good time to install the LPG intake gaskets as well.
Quote:
Originally Posted by Michael Mayben View Post
Certainly....IF you can find 'em!

I'm still looking for a supplier for the 345/392 gaskets right now.
Both LPG gaskets and the core plugs are currently in stock. These particular core plugs are not yet online however the gaskets are - Intake Manifold Gasket's for IH 4cyl or V8 Engines - International Scout Parts
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Old 01-18-2011, 04:40 PM   #8 (permalink)
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Default Re: Intake Manifold Leak?

Quote:
Originally Posted by Michael Mayben View Post
Yes, that is a VERY common vacuum leak point, actually on BOTH sides.

Pull the intake manifold, replace ALL the welch plugs you see in the bottom, (between two and five), and re-install using NEW gaskets treated with Copper Spray-a-Gasket.
Definitely replace ALL of them, I had to take the manifold off twice because I thought I could get away with only replacing one.

See here.
http://www.ihonlynorth.com/forums/ba...html#post41655
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Old 01-18-2011, 10:37 PM   #9 (permalink)
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Default Re: Intake Manifold Leak?

I just did this, be sure to drain the coolant first. You will need to pull the drain plugs on each side of the engine to lower the fluid level. Its was a bit a bitch to get them out. I used a big slide hammer and it took like 3/4 good whacks to get them out.

Hindsight. would be to pick up the HF wire wheel set first to clean out the holes and clean up the head and intake surface

http://www.youtube.com/watch?v=buxQIGlU57g
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Old 01-19-2011, 10:20 PM   #10 (permalink)
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Default Re: Intake Manifold Leak?

Thanks guys. I'll order the gaskets and plugs from Jeff in a week or so. Wasn't aware of the drain plugs on both sides of the engine, where are they located? Jeff, that new carburetor is working great, thanks to you and Michael for setting it up.
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Old 01-20-2011, 10:06 AM   #11 (permalink)
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Default Re: Intake Manifold Leak?

You may find one or both of those plugs to be majorly sealed up. Frikkin square head plug is tough to get the requisite torque on. An easiear way of draining fluid is the drain cock on the radiator or just pull the lower hose.
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Old 01-20-2011, 10:10 AM   #12 (permalink)
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Default Re: Intake Manifold Leak?

Draining the coolant is necessary, but why can't you just crack open the petcock on the radiator? Once its drained into a bucket, the coolant level is practically non-existent. If the coolant is still in good shape, just strain it and re-use it. I don't understand the need to drain the last bit out of the block (by popping the threaded plugs near the oil pan) unless you're doing freeze plugs too. Even then the block should still be sufficiently empty.
Just trying to save you some work.
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Old 01-20-2011, 01:29 PM   #13 (permalink)
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Default Re: Intake Manifold Leak?

Well if you drain the radiator and let it set for a week it might go down on its own? I drained mine and let it sit over night and then pulled the intake.

I drained the radiator and did one side of the engine to make doulbe sure it was low enough. But when I pulled the intake coolent poured onto the valley pan from the side I did not drain. The good new is none of it when into the engine. I would have thought too it should have drained down, but it did not.

Edit: I took the picture with the lower radiator hose pulled. The only reason the coolant level is not at the very top of the holes is I splashed some out to clean off the intake. I would have thought the coolant would flow out the tubes in the head to the water pump and out.
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Old 01-20-2011, 03:16 PM   #14 (permalink)
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Default Re: Intake Manifold Leak?

The coolant is land locked so to speak because of the water pump. If I recall correctly one heater hose connection will drain the water to a safe level. I would remove the bock plugs anyhow to purge crap from the block. You may have to break through the sediment with a screw diver that often blocks the plug hole from the inside.
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Old 01-20-2011, 04:10 PM   #15 (permalink)
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Default Re: Intake Manifold Leak?

Danny, as Robert said, pull the plugs down near the oil pan. this will make sure you dont get coolant in the intake runners and make cleaning the block easier. personally, i absolutely F'n hate antifreeze on me or the floor in my shop. but its a neccessary evil. anyway, after draining the antifreeze tap those holes out to clean the threads. its 1/4 npt. then pickup some radiator petcocks and put them in the holes with antiseize. then the next time you need to drain the juice, its easy as pie.
its also a great time to tap out the intake bolt holes to make reassembly easier, also giving you more accurate torque values. going back with new grade 8 bolts and hardware is a plus too. just dont forget the copper gasket spray. Happy Wrenching!!!
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