How much coolant should it eat?

[wdkingery]

89 gmc Sierra, 6.2, 230k miles.
Bought it from the original owner 3 years and 25k miles ago.
It seems to eat coolant, and I'm now beginning to track it... It's eating a 16 ounce water bottle every 500 miles or so. Definitely doesn't appear to be leaking anyway.
White smoke when you mash it, but I've learned the injection pump can retard over time and likely the white smoke on heavy accel.
Hardly uses any oil, motor has never been apart. Starts great even when cold, still gets 25+ mpg Highway. I hate to think it'll become a problem.. Almost seems normal.
Seem normal?

[DmaxMaverick]

1 qt. in 1K miles isn't a lot, but it's too much. If you can eliminate a temporary air issue, it must be addressed. Probably head gasket(s). You can try Cadilac tabs. Get them at your dealer. NO silver-solder products.

[wdkingery]

What the hell is a Cadillac tab?

[wdkingery]

I wonder what this is, you reckon it's coolant? it's on the intake manifold, but right next to some head supply coolant thing.
http://s2.postimg.org/chqe50z7t/20150429_100533.jpg
http://s16.postimg.org/b38vzshl1/20150429_100555.jpg

[DmaxMaverick]

Your pic certainly looks like it could be a coolant leak. With the volume you are losing, it's possible the coolant is steaming off before it has a chance to accumulate once the engine is hot. A relatively simple fix, if that's it.


What the hell is a Cadillac tab?

Cadillac Tablet(s). Coolant system sealant, like Silver-Solder, but not. They work well to seal minor coolant leaks, especially intake manifold seepage (what they were designed to do). They are available at any GM parts dept.

[wdkingery]

thank you for the quick response, and the detailed information.

i would like to avoid putting any miracle-honey stop-leak type goo in my radiator, GM certified or not. but thanks for letting me know they have such a thing.

[DmaxMaverick]

The tabs aren't any sort of "goo". They're solid tablets of organic "stuff" that dissolve into the coolant. Once in and dissolved, I can't tell it's there, but it works as advertised. Nearly all recent year Cadillacs (and several others) leave the factory with the stuff (hence the name).

But, if your intake manifold is the leak, I'd just fix it. Too simple.

[tomtaylor]

89 gmc Sierra, 6.2, 230k miles.
Bought it from the original owner 3 years and 25k miles ago.
It seems to eat coolant, and I'm now beginning to track it... It's eating a 16 ounce water bottle every 500 miles or so. Definitely doesn't appear to be leaking anyway.
White smoke when you mash it, but I've learned the injection pump can retard over time and likely the white smoke on heavy accel.
Hardly uses any oil, motor has never been apart. Starts great even when cold, still gets 25+ mpg Highway. I hate to think it'll become a problem.. Almost seems normal.
Seem normal?


Are you getting any excess pressure in the rad? I've had enough experience with coolant and head gasket issues to say just do the head gaskets. At 230k miles on a 6.2 that problem isn't going away. There is also the possiblity that if the head gaskets are going that the rad might need to be done as well.

If you don't want to dig into that right away then by far the best product I have ever found for this problem is www.irontite.com . I have used it successfully probably 3 different vehicles and I would only use that product because there just doesn't seem to be anything else that good around here. Whenever I need it I get it at the Kenworth dealership locally. It will take one full bottle for sure, 500ml. I have talked to several other people that swear by it as well.

BTW do not do a cooling system flush right now or you will be doing the head gaskets. I've been there done that and I ended up with way worse coolant problem. Wait until you are ready to do the head gaskets then do the cooling system flush just before you take it apart. If your rad starts pressurizing and or you have over heating problems than it's time to do the gaskets & cooling system.

Good luck

[More Power]

Looks like the coolant crossover is leaking coolant at the heads. Get the Fel-Pro gaskets for that part. The gaskets just wear out over time (years). I'd replace the gaskets before suspecting something other. They're cheap. Jim