Who are the experts on the Air compressor

GCecchetto said:

Do you guys recommend any type gasket sealant/adhesive on the unloader gasket?

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No. Installed dry. Same with the head gasket.

Okay, this saga is behind me. The gasket that came in the kit I ordered is really nice and better than than the original paper only gasket in my opinion. Also installed the 175psi secondary relief valve. Removing the original relief valve was a royal pain in the a$$. Whoever installed it buried the threads in the dryer and the wrench flats are outboard of the vent holes which significantly weaken the body of the valve causing it to snap off. Eventually managed to remove it by driving a screw extractor into it and clamping a vice grip on the out side of the barrel. Applying force to both broke it free.

Okay folks, truck is running like a Swiss watch and the issues with the compressor and relief valve on the air dryer are gone, but I need advice from the brain trust here. Surprisingly, the unloader cover is leaking all the way around its perimeter. I really thought the gasket above was going to be the bomb, but no love. I have another gasket that doesn't have the embossed sealant strip like above and am considering trying that with some of the anaerobic gasket sealant. I know many of you know much more about this type of stuff than I do, so looking for advice. I have already tightened the bolts further and really don't feel it's safe to put any more torque on the 1/4' bolts.

Are the surfaces flat? I use a flat file to draw file mating surfaces flat(pull file perpendicular to the long axis of the file like a draw knife), to reduce any raised areas… For paper gaskets I have used a spray sealant called copper coat for decades when needed. Hang the gasket on a hook and spray both sides and allow it to tack up then install the gasket..

The gaskets are installed dry......

I've done half a dozen of these with the RNT-26 kit from Haldex without issue. Check the surfaces but I would guess it's probably that gasket. I haven't seen that one before with the pre-applied sealant stripe.

Make doubly sure that unloader access plate is FLAT.

Ronmar said:

Are the surfaces flat? I use a flat file to draw file mating surfaces flat(pull file perpendicular to the long axis of the file like a draw knife), to reduce any raised areas… For paper gaskets I have used a spray sealant called copper coat for decades when needed. Hang the gasket on a hook and spray both sides and allow it to tack up then install the gasket..

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Thanks. Yes, the surfaces are flat. I used copper coat on the cork gasket I made initially. I will install the other gasket I have and see if that fixes the issue. If not, then I'll try the copper coat.

I ended up buying two kits due to a delay in shipping of the first kit. They were both listed as RNT-26 kits for the EL 1300/1600 compressor and the photos of the included parts showed the small and large unloader pistons. Both kits showed up with only the small pistons, so no o-rings for the larger pistons included. Fortunately, my pistons and springs look like new. When I installed the home made gasket, I replaced the o-rings on the pistons with o-rings from a assortment kit I have, found here. Not sure if the material is appropriate or not. If anyone knows the proper o-ring spec, please share.

I would use Viton or Silicone o-rings. HNBR might work too - those are used in refrigeration/AC systems so they can handle some oil and high temps/pressure - AC systems routinely hit 300 psi. The factory one's are Nitrile which is essentially just vulcanized tree sap with some carbon and extra seasonings. Synthetic Fluoroelastomers have come a ways since this compressor blueprint was smoked over by a (likely long dead) engineer with a tobacco pipe.

Okay, can someone explain what exactly is being said in the Haldex unloader maintenance instructions that says "Apply M-R spec 2527 lubricant to the unloader seals forming a 9/16 diameter ball around around each seal"? That seems like a huge amount of lubricant if they are literally saying to create a 9/16" ball of lubricant around the unloader piston heads, especially on the top side of the piston. Doesn't seem right. Maybe they mean a 9/16 diameter ring? I can see lubricating the piston shaft and the o-rings, but not with that much lubricant, and that wasn't what appeared to have been done when I originally removed the unloader cover.

What is everyone using for an Inlet Valve Cage tool?

If you carefully file pins on the side where they are D-shaped they can be contoured to fit in the intake valve cages. Just be careful that the force is being applied uniformly so you don't crack the cages. I've done like 5 or 6 compressors effectively with mine. Works great actually. The factory tool seems to be unobtainable in practice despite there being a part number for it - it doesn't even exist in the federal system despite the rebuild kit being listed for some 1970's fire apparatus.....

I took the head off my parts truck and rebuilt that then swapped with my operational truck and I just finished replacing all the valves on that as well so I have a spare. I found all the intake valve disks damaged even tho the springs were still intact, the disks have gouge marks from slamming into the valve cages. I think a broken spring just accelerates the wear. I’d imagine running at redline also does not help the issue. I think a head rebuild is definitely a good preventive maintenance item.

Blownaway said:

What is everyone using for an Inlet Valve Cage tool?

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I got the tool about 2 years ago, if you want to make one I have some measurements.

I think that is probably the biggest issue, running them around at max governed on the highway…