Need new heater core?

[TFatseas]

Figure I should ask for a diagnoses before I do anything...

Recently bought an 87' Town Car, has had water pump replaced recently.

Driving down the road tonight and the temp gauge was starting to bounce back and forth. It would spike and settle back down. However the car was running warmer than normal.

I took a quick look and I can't find a visible leak inside or out, but there is a definite coolant smell for a few seconds when the heater is turned on.

Any thoughts?
Thanks.

[1990LTD]

Look around the passenger floorboard and up on the firewall. The heater core is up behind the glove box. Could be a pinhole leak though, pressure test it if you can.

[BerniniCaCO3]

1990LTD is right; look for leaks there first. But until you know more, there's nothing conclusive yet.
Bouncing temperature gauge I don't think would have anything to do with a minor leak from a heater core, so, not that you shouldn't worry about it, but it shouldn't cause you to worry about the heater core.

It could be normal thermostat behavior: my thermostat I have now does not do this, but the one I had right before this one, would overheat by oh maybe 10F (making up a number), then open, then the temperature would suddenly drop, then it would warm back up again and settle there. The one I have now just warms up to operating temperature and stays there.
This would happen of course within the first mile or two on the freeway, just once, the first time the car gets up to temperature. Is that all you're seeing?
If it bounces back and forth several times on a longer trip, then you need to observe more. Is it overheating every time you're stuck in traffic or at a red light, then cooling down on the freeway? Or overheating every time you go up a hill (under load)? Or just randomly?

[TFatseas]

I plan to give it a better look over tomorrow when the sun comes up.

Anyways...

Normally, the car warms up quite a bit, the thermostat opens up and the temps drops and stays steady. However tonight, it warmed up, stayed warmer than usual and right before I got it home the temp would start to spike up and drop back down, it seemed to do it randomly.

May as well give a look at the thermostat as well...

[gadget73]

could be heater core, might be leaky hoses under the hood. Check under the hood first though. Unless the core leaks fairly bad, you wont get water on the floor. they can have a pinhole that leaks enough to make the car stink, but not leak enough to create anything obvious on the floor. If its blown bad enough to really make the carpet wet you wil definitely know theres a problem.

[mcninetyone]

Sometimes one clue to a heater core leak that is not obvious is a fog or mist build up on the inside of the windshield.
And when you wipe it away it comes back soon enough. And of course you need to look and see if you're low on anti-freeze. And if after you fill it up it goes back down faster than usual. And finally, check for signs of anti-freeze under the air conditioner drain tube. Which is on the pass. side at the firewall.

There shouldn't be any coolant smell, thats not a good sign.

[1990LTD]

Another cause of the jumpy gauge could be air pockets in your cooling system.

[GM_Guy]

Also check the hoses that connect to the heater core. If one is leaking, it can find its way into the plenum and stink up the interior.
As above: possible air pocket. Car cold, slightly nose up, remove rad cap (is it full?). bottle of coolant handy. start car. Watch while car warms up, fill to the top when the level drops, put cap back on.

Alex.

[TFatseas]

All good advice guys, thanks for your input.

Never hurts to have a place to start!

Anyways, too busy today to give a it a good going-over, will have time tomorrow.

[TFatseas]

Well, it seems to be the heater core...

Checked for air pockets, hoses et al and that all looks to be good. Can't find a leak. Did check the fluid again and it was down a little.

But when you turn the heater on you can clearly smell it. I'm guessing as Gadget73 said, a pinhole leak, due to not finding a wet spot inside.

Well, darn.

[TFatseas]

I hate to bump+triple post, but I figure this is better than starting a new thread.

What's the best way to bypass the heater core?

I don't plan to drive it in the winter so I don't care too much 'bout having heat...

Thanks

[86VickyLX]

I hate to bump+triple post, but I figure this is better than starting a new thread.

What's the best way to bypass the heater core?

I don't plan to drive it in the winter so I don't care too much 'bout having heat...

Thanks

Get a fitting 5/8" on both sides, and attach the heater hoses together. There all done.

[1987cp]

Or if you have hoses all the way, just loop the hose from the water pump around to the fitting on the intake manifold. At least, that's how I've done it in the past, and it's easy to do even in a parking lot at 11pm with no supplies other than a screwdriver.

[TFatseas]

Thanks all, I appreciate the input.

If I had a free weekend I'd try to replace the core myself, but this will do for now. Looks to be rather involved...

I can't see paying a shop $500-600 bucks when I only paid $1000 for the car.

[sly]

when I had to bypass it... I hooked the hose from the rear of the engine up to the blower cutout (that ATC connected thing back there) and left the hose that goes from that to the heater core... on the heater core. Mine had more than a pinhole leak though... good size crack in the solder joint around the driver side pipe of the heater core. I keep meaning to re-slobber that thing... it's on a shelf in my garage waiting for the torch.