I am getting early signs of intake manifold gasket leak. It sounds threadful to think about having to remove the bottom intake plenum intake manifold to replace the intake manifold gasket. My truck is still running OK not overheating, just having steam coming up from intake manifold area near the fire wall. Did not lose much water in overflow tank, maybe a half a pint of water after a 30 mile trip.

1) Will the leak stop if I can tighten or retorque (if possible) the lower plenum intake manifold bolts? Is there anyone here successfully stop the leak by tightening the bottom plenum bolts?
2) Can i get to the bottom plenum bolts without removing the top plenum intake manifold?
3) If i have to go to the worst case scenario which is to remove the bottom intake manifold, can i remove the bottom plenum intake manifold without removing the alternator and the AC compressor? I hate havng to remove things when it is not required.
Thanks

 

If I remember correctly, there is no coolant that the intake manifold gaskets seal. I think all the coolant in that area is from the head gaskets. Someone else can confirm this. The Throttle Body of course has coolant.

 

Lower intake which sits on top of the heads = coolant passes thru it.

 

You can try to snug them them down and see if maybe they were not torqued down properly from the start. Really though, if you’re that far in, just remove the gasket and replace it. I don’t think you have to pull the alt and AC comp, but not sure. Shouldn’t take that long, esp if you don’t have SIA. If you do, pull those studs for the valve brackets and reassemble with bolts.

 

Thanks for your advice guys, If I do not have to pull the alternator and AC compressor, I will probably pull the lower plenum off and replace the intake manifold gasket. The disco has only 98K miles. A little coolant was trickled into the passenger floor while I was driving 10 miles into the trip. Temperature gauge did not show high temperature. The next day I found water condensation around the intake manifold and engine bay close to the fire wall. It appeared that some hot coolant vapor has evaporated and condensed around and on the surface of the intake manifold area after the car was parked overnight. The overflow coolant tank did not lose much coolant, half a pint of coolant was lost.
Engine can still get started right up. Engine is running with a small misfire but not noticable if you are paying attention to it.

Anyway, Thanks again

 

It's not a big deal to move the alternator and compressor aside. I think you do need to move them in order to get to some of the bolts. Release the tension on the serpentine belt and then undo the four long bolts on each accessory.
You definitely don't need to mess with the refrigerant lines (just set the A/C compressor in the airbox) but you might have to disconnect the small signal wire connected to the alternator.

 

AC comp has to come off, as does the alternator. I would never take one down that far without doing the HG, you are 90% there with only the exhaust manifolds left.

TIghtening the bolts might help, be careful though.

If you run the cap one turn loose the system will not pressurize and your leak will slow down considerably.

 

Your qoute:
"If you run the cap one turn loose the system will not pressurize and your leak will slow down considerably...."

Hi Extinct, I realy want to eliminate teh leakage completely, not just to slow down considerably.. " Thank you though because you helped answer my question. Tightening the intake manifold bolts will just slow the leak down considerably but not eliminate comletely?

 

Unknown if it will stop or even slow down, it would depend on how tight they are now, if the gasket is damaged, and why it is leaking. Could be someone did not torque it properly initially and coolant is going under the gasket. Could be that you had an overheat event and that was the weak point relative to pressure and the overpressure blew the gasket at that point. If that is the case tightening might decrease the gap but would not close it. Impossible for us to tell.

 

Can always try a thread repair like Helicoil or Time Sert