MainePorsche

On my unit I have about a 25 % insulation loss.
Do you think this would cause issues ?
If so, what is replacement/repair remedy ?

Thanks in Advance,
Craig

Leon Speed

Your missing insulation on your unit?

SeanR

Pipe insulation from Home Depot or Lowes.

The stuff gets old and brittle and then flakes off.

MainePorsche

Thanks Sean.

westija

Craig, I lost almost all insulation on mine and have replaced with pipe insulation from hardware stores (threads here will show the type).
I think like many things, time makes them disintegrate

MainePorsche

Thanks as well for the reply.

dr bob

On other cars where the cosmetic issue was secondary to function, I added foil-faced insulating tape to the AC accumulator and such. It's much more effective in the high-temp environment in the engine bay, and the foil face means it's less subject to contamination from engine-bay fluids and fumes. It's sold in rolls a couple inches wide at H-D and Lowes, usually near the water heaters and such. I add a few cable-tie straps around the last layer so there's less chance of it peeling off.

MainePorsche

dr bob,
When you say AC accumulator, are you referring to the cylindrical unit up by the low pressure switch ?

the flyin' scotsman

I believe thats the drier for the a/c system.

MainePorsche

Malcolm,
That's what I thought he meant by AC accumulator.

dr bob

AC comes in different 'flavors' on different cars. Apparently, expansion valves are too expensive for mass-produced cars, so manufacturers have been falling back on to using a fixed orifice to meter liquid into the evaporator. Little plastic orifice tube, screen stuck inside to distribute the liquid and help manage pressure drop. It works OK, is somewhat self-regulating as the liquid flashes and goes sonic exiting the tube. Anyway, those systems push liquid out of the condenser into an accumulator bottle, and the liquid then passes throughj that orifice tube, flashes to vapor as heat from the cabin air is absorbed in the evaporator. That accumulator bottle sits right over the rear of the engine, adjacent to the evaporator inlet. Every calorie of heat transferred from the engine air to the accumulator bottle is a calorie that won't be absorbed in the evaporator. So it pays to insulate those parts, especially that big metal cannister where it sits over the exhaust at the rear of the engine bay.

Good news is that your 928 doesn't have one. Instead, as Malcolm points out, liquid in the 928 passes through the receiver-drier in front of the radiator sheet, where there is an extra chance that more heat will be shed to passing air on its way to the condenser and radiator. For sure you do NOT want to insulate the receiver-drier on your 928. The piping and hoses behind the radiator are all candidates, but it's tight at best and subject to wrench damage. The fuel cooloer passes 'spent' refrigerant vapor around the fuel line, absorbing heat from the fuel and passing it to the condenser. It needs the insulation and it's pretty easy to put it on there, since for the most part it's way out of normal traffic areas in the engine bay.

I 'sculpted' some pipe insulation to restore the fuel cooler a dozen plus years ago after doing the R-134a conversion. It held up for a while but eventually started to look pretty tired. It's hidden under the air filter box pretty much, but probably needs some attention one of these days.

MainePorsche

dr bob,
Always an education to read your postings.
Thank you.

worf928

At the same store where you will find standard foam pipe insulation, you may also be able to find insulation specifically for refrigerant lines. It's denser, more flexible, lasts longer and is closer to the OE foam. I know Home Despot carries it.

MainePorsche

Thanks Dave,
Good information is never to much.

17prospective buyer

Basically already been answered... but in simple terms the refrigerant is still boiling to reach it's vapor stage even as it goes through that fuel cooler, which absorbs any heat energy that is around it, so it makes sense to use the residual cooling effect to cool fuel as it returns to the tank.