02 duramax Low coolant light

[9365turbo]

My low coolant light keeps coming on after I pull a long hill empty and when I haul my camper and boat on flat ground. I replaced the water pump last year. It has 176000 miles on the truck. The injecters were replaced before 100000 according to the dealer. I have only owned the truck for a year. It also burbs coolant out when I use the block heater. During normal every day driving I have no problems with the light. Any help the forum can give me would be great. I have a feeling its going to be the head gasket or the injecter seal.

[DmaxMaverick]

It could be an injector sleeve or gasket, but the block heater usage coolant loss indicates another problem, or a combination of issues.

I suggest replacing the coolant pressure cap as a start. Check for hose leaks and cracks in the radiator tanks(replaceable) and coolant reservoir, as well as the cores (radiator and heater). If it is releasing at too low pressure (like when using your block heater), it will lose coolant when it shouldn't. Your coolant loss during block heater use may indicate it isn't an injector/gasket issue.

In the meanwhile, pull a sample of coolant and have it tested for HC content (combustion properties). Also keep an eye on your oil level and quality. If it has CA emissions, the EGR could also be suspect.

[9365turbo]

I replace the coolant res cap. first. Oil always stays up and takes awhile to turn black. No leaks of coolant. I always have pressure in the res tank when I take the cap off to put coolant back in. Where do I take a coolant sample and any idea what that cost?

[DmaxMaverick]

The tests aren't expensive (less than $20). Many shops and dealerships can do it, or send out to be done. Most oil analysis labs can do them as well. There are some "test strip" type tests available, but I've found them to be unreliable. You should also have your cap tested to be sure it is holding to full pressure.

Check your entire system very closely for leaks. Some locations can leak with little to no sign, like the turbo coolant return line behind the fan pulley.

[9365turbo]

My local dealer wants me to bring my truck in. I said no thanks. I will give some diesel repair shops a try on the testing. When I bought the truck it had a low coolant light. The water pump was leaking from its weep hole. I'll check the turbo return line. I did put a screw type clamp on it maybe its loose.

[DmaxMaverick]

I replaced my return line hose and used worm type clamps. It began leaking again after a month or two (out of town, of course). I had to use double clamps (2 at each end). No leak in about 2 years. Unfortunately, there just isn't enough room there to use larger clamps.

[9365turbo]

I checked the turbo return line and it was weeping not dripping. So I tighten the clamp. So will see on that. I took the res cap off and as always there was still pressure in the system. Truck was cold sitting since Monday. I let the truck idle for around 10 min and bubbles were coming from the lower hose with the cap off. I'm going to have the cap tested tomorrow. Also found a shop to test the coolant,but they need the truck not a sample. ($43.00) Not sure what the bubble things all about. Maybe it needs burped

[DmaxMaverick]

Bubbles = bad. Back to the head gasket or injector sleeve probability.

You could try to bleed the system, but unless there has been opportunity for air to get in (or wasn't properly bled), it won't help. Free to check this. Proper bleeding requires the engine to be ran up, and held for several seconds, at 3,000 RPM's, several times (tranny NOT engaged). This is after the bulk of the air trapped at the thermostat outlet is bled, using the bleeder port there. The reservoir level is above the bleeder (with truck on level ground), so filling the reservoir with the bleeder open should force out the trapped air. If it still has pressure under the cap after sitting overnight, it has a LOT of air in the system, regardless how it got there. Try bleeding first, and cross your fingers.

If it is bled properly and you still get bubbles at idle, you can bet the bubbles are combustion gasses. If this is the case, you could try some "Cadillac pills". Most GM dealer carry them. Ask the parts dept for Cadillac coolant system sealer tablets. Sometimes it works, if the leak isn't too bad. DO NOT use any other type of sealer in your system. If the Cadillac pills don't work, none of them will.

[9365turbo]

I will try bleeding it tonight. My drive way isnt quite level. If it is the head gasket or injecter seal. Why wouldnt the coolant burp out all the time? What are the cost for parts on such a repair? Off to work.

[9365turbo]

Well I gave my D-max the pill today. Then I opened the bleed screw and filled the res until it ran out of the bleed hole. Started the truck and let it warm up. Which takes forever. Ran it up 3k a half dozen times. Let it idle between them a bit. I did notice bubbles coming from the hose that goes to the top of the radiator during the idle times. Once I rev'ed it the last time I didnt notice any bubbles. I left the cap off for the night. Should I fill the res up to the full cold line before I put the cap back on tomorrow?

[DmaxMaverick]

Yes. Filler 'er up the the mark. If you can see the coolant level line well, mark it with a pen (some tanks are too opaque to be that accurate). Check it every morning, parked in the same place/orientation. If it bled completely (should have, or very close), the level should be the same every morning (relatively the same cooled-off time period and similar temps). Don't be too alarmed if the level drops a little the first couple/few days. As long as it levels off and maintains within a few days. Also, be sure to seal up the turbo coolant return line. It may not look like much of a leak, but can be more than it seems when the engine is hot and under full pressure. Get another pair of clamps on it, if you can. The Cadillac pills should take care of that one, as long as it was only weeping. The pills can take 4-5 (or more) warm up cycles to work completely.