Author Topic: Anyone know where this hose connects? (Read 3567 times)

Niterider11 · « **on:** January 14, 2011, 01:06:14 AM »

Just installed an m42 into the 318 i bought. I have this one hose behind the intake manifold between the firewall that I cannot seem to figure out where it connects. Its not a great pic but its the hose I am holding.

Anyone recognize it and know where it connects

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DesktopDave · « **Reply #1 on:** January 14, 2011, 10:04:03 AM »

That's part of the three hoses for the heater core. Some models of the M42 ('verts IIRC) had an aux pump to help the heater stay warm. Let me see if I can find a parts schematic.

Niterider11 · « **Reply #2 on:** January 14, 2011, 10:55:30 AM »

Thanks..I have 2 hoses hooked to the firewall on drivers side that I assumed were for heater core but I cannot figure out where this one goes

DesktopDave · « **Reply #3 on:** January 14, 2011, 11:02:33 AM »

I think the right way to hook them up is that the input hose on the heater core (lower?) goes to the plastic coolant trunk off the driver's side of the engine. The output (upper?) hose splits up - one side goes to the rear of the cylinder head and the other side might go to the radiator. It's been too long since I had that all apart, I just don't recall it clearly.

Niterider11 · « **Reply #4 on:** January 14, 2011, 11:37:30 AM »

the hose I'm holding comes from under the intake manifold cluster of hoses its prob only ten inches long it doesn't stick out from behind the motor. I can't see a connection anywhere in the area

Niterider11 · « **Reply #5 on:** January 15, 2011, 01:35:25 AM »

thanks for the help everyone i still havent found a damn spot to connect it to

DesktopDave · « **Reply #6 on:** January 15, 2011, 08:15:52 AM »

OK, I finally took a look.

Upper heater hose splits with a tee. The main part continues under the intake manifold, I suspect it runs back to the coolant plenum on the engine. The smaller part goes to a wye on the lower heater hose.

The lower hose goes to that wye (smaller hose splits off to the tee on the upper hose), then off to what seemed like the rear throttle body heater junction, part #25 in the RealOEM diagram. I couldn't be 100% sure without pulling the intake.

So I'm guessing that you've connected the upper & lower lines, so what you have there is the connection that runs between the input & output hoses. On mine it's definitely a smaller size than the input & output. Maybe there was a production change between your car's build date and the M42 you installed? Check that upper heater core line for a tee.

In the RealOEM diagram it's missing the heater connections from what I can figure out. I'm not sure about that rear connection on the head either. Looks like hose #26 is the upper heater core connection, and maybe #23 is the lower one? That's a really confusing system...

I went back through the hose delete mod post again, you can see the connection on the driver's side of the cylinder head...so I'm confused here. Check out the 2nd pic in post #23 for a good shot of it.

I'm not sure this helped much, but it's 10degF here and I'm not going outside again until I can feel my toes.

Niterider11 · « **Reply #7 on:** January 15, 2011, 09:53:04 AM »

That sounds like it should help a lot, I will check it out tonite and look into doing the hose delete mod

Niterider11 · « **Reply #8 on:** January 16, 2011, 12:40:17 AM »

Ok so I did some more searching and looking at the diagram and still cant narrow it down. I dont see any other open ends under the intake manifold or anywhere else in reach of the tube.

best way i can describe it is when you look at the bottom outlet hose on the drivers side on the firewall and follow is it curves behind the engine and connects to a round metal cylinder, i thin ICV. on the other end there are two tubes that come off, this loose one is the smaller of the two. i wont be able to fire up the engine for two days but decided to just cap it off and see what happens when i start it up and see if i can trace it at that point or if its pointless.

lbreevesii · « **Reply #9 on:** January 18, 2011, 08:35:18 PM »

Not sure if this is it or not, but to expound on what was being said:

Upper heater core hose goes to the plastic coolant tube
Lower one goes to the back of the head

There was a recall in the early 90's where they installed a bypass between the upper and lower hoses. All it involves is a small pressure triggered cutoff valve in the lower line and a small hose running to a T in the upper hose. If the end of that little hose goes to anything connected directly into your lower heater hose, you've got a bingo. Likely someone replaced the upper hose and went wtf is this? and just left it loose. So in the event of a failure in your heater core, you would dump coolant down the back of your motor rather than just having it circulate back through!