Heater core went. Have new one coming but won't be able to install before the weekend. Want to use car.

I cannot find a fitting that lets me connect 3/4" hose to 5/8" hose to bypass. Tried NAPA, Home Depot, etc. Suggestions welcome.

There is a short hose that runs from throttle body to block/intake. Is this 3/4". If so can I bypass both heater core and throttle body??

Thanks.

 

Just use a 5/8 pipe and tighten the clamps real tight and that will get you to the weekend.

 

Got mine from advanced auto when my core went. Good temp fix but it"s been three years and I can't work up the time to do a replacement so it's still holding.

89 Red Coupe

 

When my heater core wint bad and I bypased it there was a one way valve in one of the heater hoses. I pushed that into the other heater hose and put a clamp around out side of one way valve.This valve might have been plastic but it worked out great. When done I tucked it under heater box you couldn't even see that it had been done. Good luck Tim

 

If you have a autozone local, they have a 3/4 to 5/8 plastic heater hose nipple.

 

Glad to know I wasn't the only one frustrated by this! Leave it to GM to make a hose that's 5/8" on one end and 3/4" on the other! Geez! What were they thinking??? (Maybe it's another classic example of GM raiding the corporate parts bin in order to save $.13 per car...)

 

Must have been the same guy who designed the alternator over the valve cover, the almost non replaceable tail light bulbs on the earlier models, & the stupid EGR pipe over the other valve cover.

 

Exact info I needed, thanks, doing this to my '92. Alumaseal will hold for awhile but not past 2-3 weeks max. Starting to like the taste of antifreeze so I know I gotta do this soon... Off to autozone.

 

I have the FSM but, can I do this bypass from under the hood or do I need to get under the car as well? Does it require draining radiator? Could I pinch the hoses during the processes and avoid that if normally it would require a draining? I plan to do a flush and new fluid once this is done, I've tossed a lot of alumaseal in this system. Thanks.

 

89 & earlier are easy to do. Don't have to remove the dash....can be done all from underneath. removing pass. seat 1st step. Much info w/pics on this forum....worked for me.

 

You can do they bypass from under the hood. Basically what you want to do is remove the hoses that attach to the heater core on the firewall. Once the engine coolant is cold remove the hoses then install a PVC elbow(s) to complete the loop the way the heater core used to do. You can pinch the hoses off or just hold them higher than the intake when doing the bypass and you shouldn't loose much coolant. Be sure to burp and/or top off the coolant level once the bypass is complete.

 

Question on this. Can you just cap the two pieces off where the hoses used to be on the water pump? My heater core popped tonight. I just took off the hoses and put on some 3/4 inch rubber caps with a hose clamps to hold em tight. I mean if you were running an electric water pump it would be the same thing. Just wondering if it's really necessary to complete the loop or if you can just cap em like i did and have no probs.

 

bump for any thoughts on ^

 

It depends on the year/options and "stock" level of the 'vette. On the L98 don't forget that tiny the heat riser tube that comes out of the intake. Additionally, some years also have the oil cooler tied into this same coolant path.

If you have any doubt about what you have your better off just to bypass the actual problem area.....the heater core....it would be a shame to wreck a set of heads from no, low or trapped air pockets in the coolant system. A 90 degree elbow and 2 hose clamps only take a few minutes to install.

 

My vette is pretty far from stock. I'm Currently building a 396 stroker for it. But as it sits now it's far from stock also. All emissions, A/C are gone. And i'm putting in an electric pump in a bit. This car is a street car with and emphasis on drag racing. The blower motor and all that is next to go.

Here's some pics of what i did last night:

 

I see what you've done - that will work but better replace those caps (I don't imagine they are internally reinforced) with some threaded plugs....especially the one in the intake since it will have more positive pressure on it.

If it is a street car I'd keep the blower motor so you can run the fan for a semi defrost mode or for just the heater. The heater core isn't that hard to change just takes a bit of time.

 

Ah gottcha. Yeah it's a brass fitting so i'll just run down to Lowes and grab a brass cap or plug and put it on there with some Teflon. Looks like it might have leaked alittle anyway. Good idea thanks!

 

True, removing the overflow tank is 2 bolts on top and it pulls aside,exposing the heater core hoses, one above the other, different SIZE hose. Getting those pinch type clamps off without the right tool is.. not fun but needle nose combined with regular pliers, and some bloody knuckles, works. A long big flat blade screwdriver to push the end of the hose away from the core while pulling on it too, got it off. It was tight on there. Then I used a piece of threaded 1/2" by 2" pipe to join them, after first sliding a couple hose clamps on. The 1/2" pipe is tough to thread into the small hose but will do without splitting or taking it too far. I think. The other end, it went right in snug but easy, then the clamps.

I think a better approach however is just to cut the hoses IF you want to do it fast, leave the ends and clamps on the core nipples, join the hoses as above. I ended up with a lot of hose kind of bound up doing it the above way and wished I'd just cut it and joined it. Hoses are cheap, I'll do it right this summer when I put a new heater core in using the EASY way now suggested in another thread, that you can pull the passenger seat NOT the whole dash, get some other pieces and parts out of the way, and drop the heater core reasonably easy.

Topped off the water/antifreeze, burped it sufficiently I think, now I'll probably have a flush done and move on to the next fix.

 

Here's what i did to make it a bit more sturdy. Of course i busted my coolant temp in the process but oh well nothing alittle super glue can't fix. Just the plastic part broke.

 

Nice. What size plugs are those?