Just got this 88 RS and just sorting things out one by one. Just slapped on a new water pump and thermostat and need to change oil, and then slap on a power steering pump thats in the mail from another member. So I'm finding things as I go.

I noticed the heater core is bypassed. The heater return line from intake goes straight back to the water pump. Theres a plastic mechanism that the heater hoses seem to attach to which has a vacuum line going to it. The vacuum line was unplugged and taped up, and the side of the plastic mechanism has a penny size hole in the side of it. I need to ask my friend if that is why they bypassed it or if it was a result of doing it. I'm interested to know what this thing does though.

Also, the oil cap refuses to come off. It just spins. I'm wondering if theres a trick to these when they get old before I man handle it and end up pulling the valve cover to remove broken plastic.

 

That plastic thing in the heater hose "loop" is the Heat Diverter Valve. It snaps easily and usually at the worst times! That's an 87-92 "feature", it's not on 82-86 cars.

In fact when I met up with the NJ f-bod association, there was a guy there who had a leak from that valve. So he got out his screwdriver. As he started tightening it, I'm telling him to be careful... wow did I feel bad when the thing snapped on him and coolant started gushing out. Luckily someone gave him a ride to the Pep Boys next door.

When I helped a buddy do a 2.8-to-2.8 swap, his snapped as soon as he put a screwdriver to the clamps.

And years before, that same guy's brother had a 2.8 that started spewing coolant in a McDonalds parking lot... so I drove up there- and that heater diverter valve had snapped off at one of the outlets. That was my first experience with that piece of fiberglass/plastic crap.

So take it out, throw it far away, and run straight heater hose from the pump back to the heater core. The only reason GM put that in there was to make the car cooler during the summer weather. Note that the a/c still blows very cold if you run straight heater hose.

Oh and go ahead and manhandle the fill cap to pull it straight out- it's a snap-in. I would've preferred the twist style, but for whatever reason (cost?) GM went with a snap in. Mine is hard to snap out OR snap in! What a pain.

 

Dude you are awesome! Thanks alot for the info

This is what I get for getting a chevy LMAO I wanted to try and pull the cap off but was like nahh I dont wanna get hasty for no reason.

You wanna know whats bad, the time I tried to change the heater hoses on my Lincoln and the damn inlet tube from the core broke! ARGH That really pissed me off.

So is it not a good idea to just use a hose splice from the parts store? Thats what I used when I bypassed the core on my Lincoln

So maybe the broken valve piece is good news and perhaps they bypassed it for that reason instead of a leaking core. I like having a heater. Thanks again for the newb info. I'm sure I'll be back for more.

 

so your heater core is bypassed? I once bypassed mine, basically to by time until i replaced the heater core. Did the bypass in the summer when the weather was warm, was going to change the core when it got colder, but, i didn't, and was driving around for half the winter with a bypassed heater core, till finally, i tore into it and replaced the stupid thing. I'd hook it up and see what's going on, foggy windows ya know, if its busted, either put the splice back in, or....replace the core.

 

Yea I'm gonna ask my friend who sold it to me first and see why they bypassed it. He showed me the part and mentioned it was unhooked but his uncle did it and he didnt say why. Since its broke I'm hoping that was why

 

The "penny sized hole" in the side of the heater control valve, if it is on the engine side, means that the inlet/outlet nipple (whichever it happens to be) has snapped off. I've been there.. The thing costs $17 (maybe it's gone up... I replaced mine almost three years ago now) and it's not that hard to replace if broken. It's just that getting the hoses off can be a real PITA...

 

Here it is

 

Yep, that's right where mine snapped off. I bought my replacement at AutoZone, but I'm pretty sure you can buy it cheaper somewhere else (a dollar or so.. not much, but it's extra gas).

Advance Auto Factory Air p/n 74805, $17. DO NOT forget to buy new hose clamps when you buy this. Also, don't forget to check your hose ends for cracks, splits, etc, at the same time.

:edit: Just to mention, it might be a good idea to arrange the hose clamps in such a manner that they can easily be tightened/loosened while the valve is out.

 

Any reason why I shouldnt just bypass that whole disaster?

 

Well, you're in Orlando. You have a choice here, unlike I did. You can either bypass the heater core, or you can remove the valve and run straight coolant through the core at all times. IIRC, the lower hose (the long one running to the WP) is the outlet, so you would have to run another piece of hose to the remaining pipe from the intake manifold coolant outlet (the rusty pipe the missing nipple on the valve was connected to).

I would recommend against bypassing the core entirely, since Florida can get to be quite cold, and you may need either your defroster or heat or both at times.

:edit: Oh, and you may need some sort of plug that can withstand 16 PSI of hot coolant backing up behind it to block off the extra heater outlet.

 

Oh yea, I want my heat for sure! I know it doesnt quite snow here but I hate cold weather. I was trying to figure how to just hook the lines straight with that extra line. I briefly though about a possible T fitting. Might just be easier to just buy the part for 15 bucks if the local parts store has it. Least around here if it cracks in a few years there will be a parts store almost always within walking distance. I'll have to figure out what extra hose I need though since one must be missing.

 

Which hoses do you have? There should be a long one running out of the water pump, which goes to the lower core pipe (the one NOT connected to the HCV), and there should be one, the same diameter, running out of the side of the HCV to the rusty pipe you have there that runs out of the T on the front of the intake manifold, under the thermostat housing. This one is about two inches long.

:edit: If you need a pic to see what I am talking about, let me know...

 

I've got one long one which is going from water pump back to the intake to bypass all those..so that means one would be needed for the other two connectors...one from water pump to connector...and one from diverter to intake

 

Okay. I assume that the one long hose running from the water pump to the intake is the one that was originally attached to the lower heater core pipe, and that one needs to be reconnected properly. If I am correct (pic may be needed), then this hose will have a lot of bends in it, since it is a molded hose that is designed to be run behind the drive belt, snaking through bolts and such on its way. If not, then you will need to buy a section of 5/8" hose that is about three inches long (you can buy it by the foot, which may be a better idea in the long run to avoid further disaster) to run from the HCV to the intake manifold pipe (the rusty POS pipe in the right side of your above pic), and you will need to buy the hose running from (depending on the store, this is a description quote) Pipe 2 or 3 to the water pump. The first section of pipe can't cost more than about $5, and the molded hose costs about $25 with tax.

:edit: Oh, and don't forget to clean up the ends of the pipes a little before you replace the hoses. Doing so will give the hoses less to grab and hold on to, making them a little easier to take off.

 

I just picked up a heater valve at discount(I refuse to call it advance) for 16 bucks and got ripped on a molded heater hose for 12.99...wasnt sure which hose was needed but I know I've got one long one which was going from intake to pump so I figured that could be the heatern return and so I got a decent size piece of molded hose that fit on the heat valve so hopefully that will fit on intake pipe and that will be that.

I asked my buddy about it and indeed they bypassed it because the valve broke...was probably summer time. Gonna see about hookin it all up tomorrow morning before goin to work.

Thanks for all the input guys!