Heads up on heater hose sizes and thermostats

[JimAerbus,W22,2003]

I have a 2003 W22 with an 8.1 and thought it was about time to change heater hoses. rizona heat is "Death on hoses and rubber componets. Have only 29k on unit and have changed antifreze and Radiator hoses once before, but not the heater hoses.

Fun begins: The hose running from the heater is 5/8" at the heater, but where it goes into the radiator it's 3/4". Needed to buy in the line adapter at ACE hardware. Next problem: The water control valve is 3/4" and the line running from the heater is 5/8" (Another adapter). Line from the block is 5/8" and the water control valve (Heater) is 3/4 on that side too. also as an added note the thermostat is 44mm and not 55 mm. Unit sole in 03, chasiss built in may 03. No telling when engine actually built. At some point the width of the thremostat housing was changed.

Just a heads up for those getting ready to do this job. Of course later models may not have any of these problems. Jim C.

P.S. It's a twelve pack job, mainly because all lines where put on before body assemled so all GM hose clamps are pointed up. Had to cut hoses to get to clamps in some cases. Have Fun!!

[MikeT]

Be advised that WH does not supply that part of the system. Your body builder decides what heat/ac system to use and supplies those parts. Your hose size problem may only apply to the Vendor supplied heating system being used.

[JimAerbus,W22,2003]

Yeah Mike, I know that, but the original vendor must have supplied hoses that where 5/8 on one end and 3/4 on the other?? I of course don't have access to them, and I didn't want to put on the standard hoses anyway. Went for the orange 250psi hoses from Napa. Was just surprised that all hoses not same size!! Had to jump through a bunch of hoops for no good reason that I can see. Jim C.

[EngineerMike]

I wonder if 1/2 (OD of which is pretty close to the ID of "5/8" hose) x 3/4 copper pipe adapter would do the job? Anybody use copper line in their heater hose projects over the years?

If you could, then some cheap plumbing fittings and some good straight hose would supplant fancy purpose-built hoses w/kinks and flared ends.

[Full-Timers]

Huh... I've seen radiator hoses with two different diameters on either end but not heater hoses.

[mfire1339]

My local " Auto Value" parts store stocks 3/4 x 5/8 heater hoses. They were used on Ford cars for many years. Forget adapters and new possibility for leaks.

Mike

[Rick Long]

Now wouldn't that be fun if you burst a hose out here in the desert..
With only tiny little towns many miles apart and no major parts stores.




Think I'll go out and check my hoses..



I should go buy some spares