How to repair a cracked Intake Manifold (1 Viewer)

[hank14]

Well, I finally took the time to swap the manifolds out.
New Remflex gaskets and a pretty, rebuilt manifold. My original one had some substantial exhaust leaks and the heat riser plate was toast, but at least the intake manifold was not cracked like I thought.

Problem is- it's still backfiring when I let off the accelerator to shift gears the engine's cold and pinging a little under load. Those 2 problems may be due to my inexperienced carburetor rebuild.

Here's a few pictures:

With the old manifold off and the Remflex gasket in place.

Getting to that last bolt- it's a tight fit back there.

Buttoning everything up.

Notice the brand new heater hoses- Cruiserdan said that J-hose on the driver's side firewall was the last one in the USA.

 

[hank14]

Keeping all the manifold bolts loose to wiggle things around, and being able to move the exhaust "horns" around some was the key for me lining all the bolt homes up and getting everything started.

Nice, quiet exhaust (with SOR SS j-tube) and a good 18 reading on the vacuum gauge.

 

[Butt Ugly Chuck]

Good on the repair. Must be nice having beat the exhaust leak!

Getting to that last bolt- it's a tight fit back there.

Gawd I hate THAT bolt!

Butt

 

[hank14]

No doubt- I was actually able to get a Sears 1/2 drive 14 mm impact socket and use my 3/8 inch torque wrench with a 3/8 to 1/2 adapter to get it torqued down right.

It's just difficult to get the bolt started.

FWIW, the SOR stainless block off plate is installed and the heat riser flap diverter is trimmed, and it doesn't seem to take any longer to warm up than it did before.

 

[TB83]

I just came across this thread, so hopefully its not too old to revive, but would you say its a bad idea to remove the flap entirely? Also, the guy at the machine shop is suggesting that he just fab up a plate from copper to in effect act as a gasket as well as a block-off plate like SOR sells. Based on your experience, would this work? Would removing the flap all together cause any problems?

FYI i already have the remflex heat riser gaskets, but he suggested they may be too thick...

 

[Spike Strip]

I don't think you can remove the flap entirely as it is what keep the rod in place... And since you're in CA, if that thermo-spring thing is missing you'll fail visual smog inspection.

I like what hank did with his. I just "locked" mine in the open position with the SOR plate installed, but hank's is cleaner. I don't see any reason why a copper plate wouldn't work as well as the SOR plate.

Did you get your carb fan working ?

 

[TB83]

Did you get your carb fan working ?

When you say carb fan are you talking about the fan clutch or something else? I still haven't gotten to the fan clutch, which is a top priority before i button everything back up. Just finished college and I am moving back to the bay area come saturday, so I've been trying to balance a bunch of stuff all at once.

 

[Spike Strip]

Congratulations on the graduation... Now just try and find a job...

Carb fan is the blower fan on the driver's side fender that blows cool air on the carb/intake when you turn off the motor.

Fan clutch is different - and if yours is not working, it can be rebuilt cheaply by replacing the silicone oil - search and ye shall find.

 

[TB83]

Congratulations on the graduation... Now just try and find a job...

Carb fan is the blower fan on the driver's side fender that blows cool air on the carb/intake when you turn off the motor.

Fan clutch is different - and if yours is not working, it can be rebuilt cheaply by replacing the silicone oil - search and ye shall find.

Yeah my plan was to follow the write up you did on it not too long ago. I've go t a job all lined up, starting at the end of april, so i have a few weeks off to finish up this project, as well as a few others I want to do around my house back home. Ill keep going with it on my other thread.

 

[hank14]

I just came across this thread, so hopefully its not too old to revive, but would you say its a bad idea to remove the flap entirely? Also, the guy at the machine shop is suggesting that he just fab up a plate from copper to in effect act as a gasket as well as a block-off plate like SOR sells. Based on your experience, would this work? Would removing the flap all together cause any problems?

FYI i already have the remflex heat riser gaskets, but he suggested they may be too thick...

I don't think you'd have a problem if you removed (cut down or try to unbolt) the flapper completely- especially since you're in CA where it's warmer.

I was concerned the way I did it might restrict exhaust flow until the flapper opened, but it seems to be working fine- even starting in cold weather.

The Remflex gaskets may be too thick- you'll need to bolt the 2 together and see if the intake and exhaust line up and the bolt holes are all round and even before you decide.

I don't know how the copper gasket idea would work.

Don't forget- if you're in CA where you'll always have to pass emissions- you might come out ahead buying a new manifold assembly and calling it good.

I'd probably talk to Mark A. at Marks Off Road to see what he thinks.

 

[alaubhan]

Hey everyone. This manifold leak is what sounds like is happening to my truck, but I want to describe a few symptoms before I go in ripping it apart.

The vacuum leak does not occur unless the truck is hot and driven a while. At startup and idle, the truck sounds great. I notice the issue when slowing down for a stop, the vacuum starts to fade and the truck is about to die. I need to rev the gas a little in order to keep the truck from dieing. The other day, I test drove the vehicle then it the symptom started, but by the time I got home the problem went away. I tried the propane/ starting fluid trick but I cannot seem to get it to rev.

Any thoughts, additional tests, or comments?

 

[Butt Ugly Chuck]

Hey everyone. This manifold leak is what sounds like is happening to my truck, but I want to describe a few symptoms before I go in ripping it apart.

The vacuum leak does not occur unless the truck is hot and driven a while. At startup and idle, the truck sounds great. I notice the issue when slowing down for a stop, the vacuum starts to fade and the truck is about to die. I need to rev the gas a little in order to keep the truck from dieing. The other day, I test drove the vehicle then it the symptom started, but by the time I got home the problem went away. I tried the propane/ starting fluid trick but I cannot seem to get it to rev.

Any thoughts, additional tests, or comments?

Under compression braking your vacuum drops? Is that conclusion based on a gauge reading?
Butt