jpc647

1972 Cutlass S, 350 ci motor, TH350 Trans.

Are the heating hoses, supposed to be different diameters? I mean, both hoses going into the heater core. My supply hose running from the water pump to the heater core is 3/4" hose, while the return hose going into the back of the intake is 5/8". Is this right, or should they both be one size or the other, and what size should they be?

Thanks!

442Harv

yes two different sizes.

Octania

Helps prevent confusion, right?

joe_padavano

Olds (and GM) did this a lot to help prevent assembly line screwups. For example, the two bolts that hold the lower steering shaft to the rag joint are two different sizes. The flare nuts on the brake lines are different sizes. Where parts can be installed incorrectly, design features like this are usually incorporated.

jpc647

Okay perfect. Thanks!

1970-W30

JPC647, not to be a nit-pick, but the 3/4 hose from the water pump is not the supply hose but the return hose and the 5/8 hose from the back of the intake is the supply hose. You had it backwards.

jpc647

Nit-pick welcomed! It'd rather be corrected, than find out the hard way some time in the future. Thank you.

Also, you rolled and burned a w30 in 75? I bet there is an interesting story behind that one!

RetroRanger

what happens when the heater core is bypassed ? typically the waterpump is then plumbed to the intake manifold...use the 5/8" ?

also what size is the bypass hose that goes from the front of the intake to the water pump (assuming same 72 350 350 setup)

Sampson

Thanks for sharing this tidbit Joe. I have often wondered why on all 3 of these items?

oldcutlass

I've never been too concerned with it and have used 3/4 on both with no problems.