Hello all.

I have a, well it’s my fiancés, 1996 lt1. So over the last 12-15 months. The rad was leaking near the tranny cooler bung. So we replaced it... we had a cooling issue, it keep dieing when warm and running fine when cold, so we replaced the coolant sensors. The low coolant light keep going off, so we replaced that. A rock somehow made its way up in to the compartment that houses the overflow reservoir. So we replaced the. A bout a year ago we did the opti (x2 first one went bunk after two months ), new water pump and thermostat and all new hose. So we have replaced and bleed the anti freeze at lest half a dozen times... we still get no hot air when its is at temp.

Would you flush the heater core, or is it just easier to replace it and not have to worry about soaking the opti, because I do not want to do that again.

Thanks
xzod

 

Do the heater hoses get hot at all when the engine is hot?

I'd try flushing it first. Many people have done it without a problem with the Opti. But if you don't feel you can protect the Opti adequately, go with the replacement, assuming it needs one.

4th Gen LT1 F-body Tech Articles

 

When i had to change the coolant resouivor last month, whe she got home i feet the top rad hose and it was hot. We werent sure were the leak was coming from at that time. But i dont remeber if i felt the heater hoses them self. i will doing that tonight. this has beed a problem for the last year. heading in to summer it wasnt so bad, but now she wants heat for some reason. lol.

im gonna try and flush the core this weekend. i figure if i put a cut milt jug under the water pump i should be able to catch most coolant that comes out. and ill just extend the hoses with some couplers and tun it away from the engin bay. should be good in therory.

 

I wouldn't worry about soaking the opti. It is nowhere near the heater core inlet/outlet. Grab ur garden hose with a trigger nozzle and shoot it carefully into the heater core (at the firewall) inlet and outlet. I used a fair amount of pressure on the inlet, then outlet, and back and forth a couple times just to be sure. You will see a good stream come out each side. Also, when I bled my system, I bled the large hose to the t stat first, then the small heater hose second. It may take a couple of tries.
This is the method that worked for me. Heat is nice and hot.

 

If you take the time to read Shoebox's procedure you will see that the easiest way to flush the core is to pull the heater hoses off the water pump. Hence the concern regarding the Opti.

 

This is just the way I thought to do it. It was easier for me to pull the two hoses off at the core instead of the wp. I doubt this solution will actually work for anyone but me.

 

If you want to make sure there is no clogging going on in the hoses, you need to flush at the water pump end. IMHO, why flush it if you are not going to flush all of it?

 

And don't forget the flow restrictor in the heater hose that supplies coolant to the core - a possible source of blockage.

 

IT is very easy to replace the heater core and aftermarket parts are not expensive. I had mine flushed, it worked for a season and plugged again. Flushed it again and it lasted half a season. For what i spent on flushing I could have replaced it.

 

You paid someone to flush your heater core??????

 

Yup. In the middle of winter with no heat and I was working 70 hours a week. Not worth it to DIY. Most things that require disposal of hazardous liquids, I pay someone to do anyway. In the winter I sometimes even pay someone to do brakes or other simple repairs and I always pay someone to change the oil at any time of year. It just is not worth the hassle of disposing of it. If it is not fun, I do not work on my cars. When it is fun, i.e. I have time, the weather is decent, my sons are around to help and learn, and I do not need the car immediately, then I will do work myself. A lot of things are simple enough that it is faster to do it myself than it is to have it done. Those things I do myself if it is not winter. You get to 20 below zero and it is no fun at all to work on a car, not even in the garage.

Thus, changing out the heater core in the spring was a nice easy job and fun to do with my son. Flushing the heater core in the winter? No thanks.

 

Flexible Hose Clamp Pliers | Toolmonger

Last week I had to tackle a badly leaking radiator that I was nursing all summer down here in sunny Florida and prior to jumping in, I managed to gradually gather all of the new hoses for the engine from front to back... including the duals to the fire wall heater core/water pump interface. I wasn't going to change the inoperable heater core because most of the time, I seldom have a need for cabin heat... but I thought..."In for a Penny...In for a Pound" and decided to pull the trigger on a brand new Delphi Heater Core for around $28.00 on eBay.

You never think about the Hodge-podge of hose clamps that have to be navigated when doing everything all at once until you've invented new swear words from having to remove and install Constant Pressure Steel Clamps and having them pop out of the vise grips or pliers we tend to use. After finding it almost impossible to reach well up under the firewall cowling area and get enough mechanical advantage with an assortment of extra-long needle nose pliers, I Googled another tool solution and found the one in the attached image at Sears. This tool was a Life Saver! It can be applied to almost any size spring clamp; from the very small to the very large and after squeezing down remotely, the device locks and holds the clamp(s) in limbo so they can be easily slid on and off and then when the release is pressed, it allows the clamps to settle as you maneuver them into the proper final positions. Well worth $35.00. There are quite few quality variations on eBay and other tool outlet sites for this device, too:

Flexible Hose Clamp Pliers | Toolmonger

One last helpful hint... After stuffing the new heater core in place, do not re-attach the half-moon holding clamp for the Heater Core in/outflow pipes at the firewall before you slip both hoses on as far as they will go!!! The best way to do this is to use a small section of 2" X 4" bracing one end against the vertical flange of the new heater core under the dash panel (no plastic outer cover installed) shielded with some folded cardboard to avoid damaging the core and then brace the other end against the apex bottom of the passenger seat cushion/seat back and then slide the seat forward gradually until there is enough pressure to push firmly on the heater core and hold it in place. This makes applying the hoses from inside the engine compartment a breeze!