How to bypass the heater core to stop the engine overheating

[Flat4]

 Peanut_xtra said:

I think I have a blocked heater core and can't be arsed changing the heater core myself, how much would I be looking at if I got a workshop to do it?

Replacing the heater core isn't cheap through a workshop, as it involves removing the dash and bleeding the system etc. I got a few quotes a while back and they were all around $800

[Guest]

Thanks heaps for the info Boostin! Saved me alotta time and $$! ;D

[SUBV3]

Hey everybody, just a new member on here. I just bought a V3 Sti and have replaced the thermostat and got a radiator flushed and service, but it seems like this heater core thing might be the problem as when i boost on long drives it still overheats. can anyone on this forum help me do this on my wrx.

[Firenza]

Have you had the coolant tested yet? My v3 was overheating randomly and a TK style test detected combustion gasses in the coolant.

Better to be sure then to replace the heater core and it not be the fault. No point throwing parts at it. Get it tested and get it fixed correctly first

[Guest]

If your Subaru is overheating first look for obvious causes, Crack in hot end of radiator in end tank (end opposite radiator cap), check for any weeping around the crimps that hold the end tanks on also, loose or weak hose clamps, small splits in heater hoses and check inside carpet for signs of moisture which would indicate a leaking heater core, Then with the car running and warn feel top and bottom radiator hoses if top is hot and bottom is cold and the radiator fans are turning on and off then replace the thermostat (use a GENUINE one) also feel the heater hoses, they should both be hot, if one is hot and one is cold there is a blockage inside the heater core. Next you need to get hold of a chemical tester and test the cooling system for signs of combustion gasses in the cooling system, This is just a general outline of a few indicators of issues. Also don't forget the obvious problems like lack of antifreeze anti-boil (except for motorsport events where you can't use it) and noisy/leaking waterpumps.

[Guest]

Just a Note: This bypass is a plausable way to resolve Minor overheating caused by lack of flow through the heater core but ideally you should think of it as a temporary measure and plan to replace the heater core at some time, Best way is to get hold of a second hand one and get it flushed and tested by a radiator repairer to make sure you have a perfect replacement ready to go in, Most Subaru cores are well made so can be repaired unlike some jap ones that are just crappy plastic and cannot be fixed.

[Stodart]

the reason why this happens is lack of maintenance!!!!!!!!!!!!!!

if the heater core is blocked then its a good chance the the radiator is getting blocked as well.

ie flushing radiator, removing 2 engine bank drains and heatercore every 2 years.

l learn this from saving my 10 year old 86 leone with 200k which had a blocked heater core bypassed this with a piece of copper pipe then still overheating, flow tested radiator was 85% blocked tanks off and had to be physically rodded out by radiator specialist. so managed to save it no thanks to previous owners

[turborunner]

ive seen guides on people putting bleach or drain unblock cemicals in heater core and leave it for awhile then block off the air compressor hose with a clamp and put an attachment on not your air gun but the bit before the air gun and put it in the hose to the outlit of the heater core and release the clamp so alot of air pressure gets released into heater core and pushes the crap out is this plauseable?

or will it create a leak in the core so your cabin gets wet as ive got a partial block in my heater core and have tried back flushing just with the garden hose and have also added two brass t-joins to bypass core just incase havnt overheated yet been running car atleast two year like it is but i do get the odd cold air through the heater when cruising down the road.