Coolant Issues

[Delta.Speed]

Hello everyone. Back again for another chapter of why I can't get my LB7 back on the road after throwing over $13k at it in performance parts just to make it reliable without actually making any power lol

Just last night I finished putting the truck back together after replacing the injector hold downs on it for the third time after I got served bad hold downs from SoCal Diesel that kept breaking. I've got a separate thread on that called "Sound coming from airbox."

Today, I took the truck up to operating temperature by idling it while simultaneously filling up the coolant reservoir and once it got warmed up it started blowing bubbles in the reservoir and overflowing with dark coolant. I'll attach pictures of what it looks like. The coolant was brand new as of this morning.

The entire top end of this truck is brand new zero miles since I haven't been able to drive it due to the hold-downs that kept breaking. Here's what's done to the truck that I think is relevant to this issue.

- New Grade C head gaskets from Mahle.
- Reman Industrial Injection heads with the Torque Lock cups. Basically screw in injector cups.
- XDP conical springs and push rods.
- Billet injector hold downs from Industrial Injection.
- ARP head studs.
- All new relevant gaskets in the top end when the heads were replaced.
- Lincoln Diesel 30% over injectors.
- New DHD high pressure lines.

I've already checked to make sure I didn't somehow get the head gaskets on backwards. I've got the L on the driver's side towards the back and the R on the passenger towards the front of the head.

It's also worth mentioning that when I was filling up the coolant I noticed a very slow drip coming from the back of the passenger side head. It was extremely slow, maybe like 1 drop every 30+ seconds. It went away on its own before I could see the source so I thought it was just residual liquid in the valley from parts cleaner or something. I cleaned the area and dried it with shop air and the leak didnt happen again. Now I'm thinking maybe it was coming from the head so if I have to tear back into the truck I will start with the passenger side.

So I'm pretty sure I'm going to have to tear into the truck again but before I do I want to hear from you guys what you think could be wrong here.

Seriously frustrated with this thing. This is my first diesel truck but I've been building gas engines for years and have never had so many issues with a simple top-end refresh.

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[Chevy1925]

do you have a pressure gauge you can stick on the bottle and see if its forming a bunch of pressure in there? bubbles could just be from whats left in the system but we dont want a bunch of pressure.

are you sure the dark coolant is not residual from the radiator prior to new engine?

 

[Delta.Speed]

do you have a pressure gauge you can stick on the bottle and see if its forming a bunch of pressure in there? bubbles could just be from whats left in the system but we dont want a bunch of pressure.

are you sure the dark coolant is not residual from the radiator prior to new engine?

I have a coolant system pressure tester that I'm gonna throw on it once I've put back what I took off to check the head gasket flaps. I'll let you know what I get. What kind of reading should I be looking for? Is ANY pressure in that tank okay?

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[Delta.Speed]

Anyone know if the starter on a Duramax is strong enough to bend a rod?

Since its been sitting with coolant in it for a while I wouldn't want to just start it in case a cylinder bow had coolant in it. So Id prefer to check that it spins freely before starting it up.

If I crank it manually using a jump switch to make sure it spins before starting it am I still risking bending a rod? Or will the starter just be unable to spin it?

I could also spin it with a breaker bar but its a pain to do with the radiator shroud in place and the belt on.

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[Delta.Speed]

I got the cooling system tester on it at 15 lbs to check for leaks while I finish prepping to start again.

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[2004LB7]

I don't believe the starter can bend rods but I wouldn't want to test that either.

As James said. Maybe it's just air in the system from filling it up. Did you loosen the bleeder screw on the thermostat housing to let the air out? Even so, often times there is still enough air in the coolant to drop the leven in the bottle an inch or two after driving it a bit.

Check for hard radiator hose after sitting overnight. That may be a better indicator

 

[Delta.Speed]

Well its been 20 minutes and I lost about 1 psi. So I'd say if there is a leak it doesn't seem to be major.

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[Delta.Speed]

I don't believe the starter can bend rods but I wouldn't want to test that either.

As James said. Maybe it's just air in the system from filling it up. Did you loosen the bleeder screw on the thermostat housing to let the air out? Even so, often times there is still enough air in the coolant to drop the leven in the bottle an inch or two after driving it a bit.

Check for hard radiator hose after sitting overnight. That may be a better indicator

But is it normal for that air in the system to make the reservoir overflow at idle with the cap off?

The overflowing more than anything is what got me because when I bought it with a blown head gasket it would also overflow and smoke out the reservoir. There's no smoke now but it is overflowing.

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[Delta.Speed]

I don't believe the starter can bend rods but I wouldn't want to test that either.

As James said. Maybe it's just air in the system from filling it up. Did you loosen the bleeder screw on the thermostat housing to let the air out? Even so, often times there is still enough air in the coolant to drop the leven in the bottle an inch or two after driving it a bit.

Check for hard radiator hose after sitting overnight. That may be a better indicator

Dude... I think your comment saved me from tearing down half the motor again. After you mentioned the bleeder I got curious and I think I know what my problem is.

I already knew about the bleeder and had read that the bleeder screw needed to be loose while filling up coolant, but mine for some reason does not bleed at all unless it is completely off. I had it loose before but still on and it wasn't doing anything. Well I unscrewed it all the way off and a crap ton of air came out and the reservoir went fully dry.

To test my hypothesis I screwed the bleeder back on with just one thread and filled up the reservoir and not a peep of air came out of it. As soon as I unscrewed it off completely same thing happened. A bunch of air came out and the tank went dry.

I think mine for some reason only drains with the screw all the way off. Maybe its the corrosion on the screw.

Anyway I'm going to fill this all the way up with the screw off and see what happens. Ill update the thread.

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[Chevy1925]

Dude... I think your comment saved me from tearing down half the motor again. After you mentioned the bleeder I got curious and I think I know what my problem is.

I already knew about the bleeder and had read that the bleeder screw needed to be loose while filling up coolant, but mine for some reason does not bleed at all unless it is completely off. I had it loose before but still on and it wasn't doing anything. Well I unscrewed it all the way off and a crap ton of air came out and the reservoir went fully dry.

To test my hypothesis I screwed the bleeder back on with just one thread and filled up the reservoir and not a peep of air came out of it. As soon as I unscrewed it off completely same thing happened. A bunch of air came out and the tank went dry.

I think mine for some reason only drains with the screw all the way off. Maybe its the corrosion on the screw.

Anyway I'm going to fill this all the way up with the screw off and see what happens. Ill update the thread.

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little angle grinder action to slot the botl threads would cure that. just leave the bolt out and fill till it overflows.

my post about checking pressure was more about while it was running to see how much pressure builds in the system. so youd leave the pressure tester hooked to the bottle but dont pump it up. Start truck, let it run and see how much pressur eit builds. you should see very little pressure till the vehicle is getting hot, after thermostats open.

 

[ikeG]

The starter is powerful enough to bend rods when compressing coolant. I've personally experienced it and then personally repaired it lol

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[Delta.Speed]

Back in to update the thread.

My issue was the bleeder screw. As recommended above I filled up the coolant with the screw completely off until coolant came out and then filled up the rest of the way.

I let it idle for 30 minutes with the pressure tester hooked up to the reservoir and had no pressure on the gauge at all. There was a very light hiss when I unscrewed the tester same as you'd expect when removing the reservoir cap with the engine hot, but no gurgling sounds or air bubbles in the reservoir.

So the black coolant must be left over from when it was pressurizing the cooling system before when I first got the truck.

I'm going to take it to my buddy's shop tomorrow to borrow his coolant flush machine to properly drain and replace all the dirty coolant.

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[Delta.Speed]

The starter is powerful enough to bend rods when compressing coolant. I've personally experienced it and then personally repaired it lol

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Good to know for future reference. Would NOT like to make that mistake.

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[Chevy1925]

Back in to update the thread.

My issue was the bleeder screw. As recommended above I filled up the coolant with the screw completely off until coolant came out and then filled up the rest of the way.

I let it idle for 30 minutes with the pressure tester hooked up to the reservoir and had no pressure on the gauge at all. There was a very light hiss when I unscrewed the tester same as you'd expect when removing the reservoir cap with the engine hot, but no gurgling sounds or air bubbles in the reservoir.

So the black coolant must be left over from when it was pressurizing the cooling system before when I first got the truck.

I'm going to take it to my buddy's shop tomorrow to borrow his coolant flush machine to properly drain and replace all the dirty coolant.

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good to hear. i understand the paranoia you probably have right now with your other issues but its always best to just step back and look at the simple things first. everyone falls for the worse case problem, including myself lol.

 

[Delta.Speed]

good to hear. i understand the paranoia you probably have right now with your other issues but its always best to just step back and look at the simple things first. everyone falls for the worse case problem, including myself lol.

Dude, you have no idea the levels of paranoia! Lol I've been driving the truck to test it for only a couple of days and I have this constant feeling of impending doom that it's just gonna blow up any second

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