first duramax, maybe bad head gaskets?

[Achay47]

I'll start by saying that i know that there are a million forums out there and they all have their fair share of head gasket failure discussions but as i am new to forums and not quite sure the formalities of them i felt it better to start my own. This is my first vehicle to be modded beyond simple bolt-ons. I will start by describing as much as i can about the vehicle. I just bought a 2001 2500 lb7, first duramax i have ever owned or chevy for that matter, left my 7.3 for something different. There are a few things done to the truck that are explainable but i do not agree with. It has 134k miles on it and i bought it from a performance diesel shop in the area. They got it with a bad set of injectors in it and redid them. They sent them to industrial injection and got them rebuilt now 65% larger then originally. CP3 pump 85% over. EFI live with DSP5 switch. Suncoast built tranny. Here is the funny part, they left the stock intake on and its the stock exhaust back with the muffler cut out. Now to the problem. When i test drove the truck they had just got done putting it all back together a couple days before. It ran great but the low coolant light was on so naturally when i got back to the shop i pulled the resevoir cap off and it damn near blew it out of my hand and shot coolant all over the place. I didn't think much of it other then i thought i might have taken it off to fast. The shop explained that they had broke a coolant line off the firewall for the heater core when doing the injectors, which was true. I filled it up and the truck ran great until today the light came back on, this time i took the cap off slow and it still exploded everywhere. since this morning i have put about 130 miles on it and put about 2 gallons of coolant in it and have yet to see a leak externally except all the coolant blown all over the side of the truck from the over flow and running it with the cap loose. I stopped by work and got an oil sample and coolant sample that i am going to send in but i want to see what anyone on here thought as well. If the head gaskets are bad i will end up doing them myself but will need some help along the way . The truck has tons of power, more then anything i have run with and i haven't even flipped the dsp5 off of stock tune. It does not misfire it does not overheat, nor does it run hot sooooo where the heck is all the coolant going? Sorry for the long post just naturally frustrated and want to be thorough.

 

[WarWagon]

I would replace the cap. Obviously the warning to not remove the cap when hot is missing.

NEVER EVER REMOVE THE COOLANT CAP WHEN THE ENGINE IS HOT!!! You can not crack the cap to relieve pressure because you are simply boiling the coolant off like a giant steam boiler powering a locomotive steam engine. You pose a scalding burn risk to yourself and others in the area when you try and take a cap off a hot cooling system.

Water boils at 212 degrees. The thermostat opens around 195 degrees. Coolant mix will boil at a different higher temperature. The heads of a hot engine are above this 212 degree boiling temperature. So if you release the up to 16 PSI pressure of the system that keeps the coolant from boiling it explodes out the filler hole the cap was plugging like a shaken up soda. To bad it is over 195 degrees and will seriously burn you! You will loose a good amount of coolant when the system is opened like this.

What you need to do is properly fill the system cold. This involves opening the air bleed screw on the thermostat housing. Leaks on these engines can boil off hot parts depending on where it is. A pressure tester on the cooling system will show you if you have a leak by pressure dropping.

Is there any warranty from the shop you bought it from? Why did you buy a truck with a low coolant light on without knowing why first? Regardless you may own it now and need to get it fixed.

After reading the above I would recommend you get it to a shop to properly check the coolant level and do leak test. You may find it is a simple bad float in the coolant fill tank tripping the low coolant light. Or they may catch a bad heater hose or leak about to let go and become an engine ruining event. Water pumps do leak and are NOT fun to change. Check the weep hole. The fan is on an idler bearing as the water pump is gear driven. $100 spent to save a $7500.00 engine.

 

[btfarm]

Bad coolant cap is common. Does the upper hose collapse when the truck is cooled down? That's another indicator of the coolant cap being plugged.

 

[Achay47]

Thanks for reading and replying, I am a diesel tech for a living so I understand the dynamics of how the coolant system works but thank you. I will try a new cap for sure, but the one that is on there appears to be brand new, I took a look at the water pump too, I did not see anything that was out of the norm and this morning I sent my oil sample in. I left one in a clear bottle to see if the coolant would separate from the oil over night but it appears to be just oil. Just now I put a pressure tester on the system and put fifteen pounds of pressure on the system it leaked about three pounds in 30-45 minutes but the hose one the gauge leaks a bit if I spray soapy water on it. then I ran the truck while it was hot with the pressure tester on it to see if the gauge would spike when I romped on it a few times but it does the opposite and pulls a vacuum on the system and drops about three pounds or so, then back at idle the pressure comes back up in the system where it originally was. The truck runs consistently at about one tick and a half below two hundred even after an hour of driving it. I have been running it with the cap loose after the second time of putting coolant back in it but today I will get a new cap and run it with it tight and see what I come up with. I have to make a two hour trip today so wish me luck

 

[Achay47]

Oh and as far as buying the truck with the low coolant light on, when I test drove it he had the heater core bypassed because he broke one of those lines on the fire wall and it was low on coolant so I figured it was a valid reason, when I came to look at the truck again the line was fixed, it was full of coolant and the light was off.

 

[btfarm]

Normal temp on these stock is 205 but the factory gauge isn't dead nuts at all. Usually fairly close. I have no clue why you are pulling a vacuum on the cooling system or even if that's a normal condition. I've never run with a leakdown tester in place.

 

[THEFERMANATOR]

Normal temp is 180-185 without a load on the back normal running. The stock gauge will tell you roughly 200-210 with the engine at 165-225, so don't believe it. As for your injectors, wish you luck. You can ask Pepperidge here how happy he is with his 45 overs from them with 25K miles and 5 out of 8 are GONE! As for the coolant issue, if you don't fill and burp the engine properly, you will be fighting a losing battle. There is an air bleed at the T-stat housing(12 MM bolt in the top of the housing towards the front center) that needs to be open when you fill it. Once coolant burps out it, I like to next remove the upper radiator to coolant tank hose and continue filling until coolant comes out the radiator side. This gets 98% of the air out so you don't have to keep topping it up all the time. If it is pushing coolant out, then most likely they disturbed an injector cup when they did the injectors. Early duramax's did have some issues with head gaskets, so you can't really rule that out either. Once you get it burped out drive it and let it cool off again and top it back off. Go out and drive it a few miles, then let it sit overnight. Before you start it go out and see if there is pressure in the cooling system. If there is then chances are you have either a bad head gasket or injector cup leaking.

 

[WarWagon]

From a cold start you can feel the upper radiator hose. If it gets hard quick it is a sign of head gaskets.
The heater core connectors are over a hot turbo on some years - so coolant leaks can boil off with no puddles on the ground.

The vacuum is normal as the water pump puts pressure on the engine up to the thermostat and is 'sucking' on everything else. With the pressure test you did head gaskets would have built more pressure up so IMO they are fine.

Water pumps can leak badly and then seal back up. Esp. if they have been run dry. They don't stay sealed long after that...

It is possible the thermostat is sticking combined with a weak cap. The temperature gauge is proven to be intentionally numb on some years not moving over a 40 degree range.

New parts never mean "good" parts. Always start over on diagnosis after replacing a part and the problem is not fixed. The amount of garbage new/painted rebuilt parts out there is stupid insane. I lost a 6.5 engine with a brand new radiator and radiator cap in part because the cap was defective. Didn't release when things got hot, suddenly blew off shock cooling the block scuffing a piston, and then sucked the hoses flat after cool down.

 

[Achay47]

Alright sorry for not responding for a while as i have been terribly busy. Thanks for the tip on the air bleed on the t-stat housing i will have to try that. Last week i had to take a two and a half our drive for work and i figured for the hell of it i would just throw a new resevoir cap on it even though the one on there appeared to be new. I then filled the truck up with coolant and took it on down the road. It did not give me a single problem for almost a week so i was naturally relieved! Then on friday i stopped at the bank and i came back out and there was a massive puddle under my truck from the resevoir overflow. I popped the hood and the upper radiator hose was rock hard even after it pushed all that coolant out the over flow. i again needed to make a nother two hour trip so i had no choice, filled it up again and headed on down the road. made it about twenty miles and the light came on again and i filled it up again. i kept doing this until i decided i didn't have time to keep stopping so i drove the rest of the way. when i arrived i was taking care of my business and when i came back out the water pump was pissing coolant out now too and again the upper radiator hose was rock hard. Since then it hasn't leaked a single drop from the overflow or water pump granted i have the cap loose right now which i know isn't the best idea but its what i can get by with for the time being. any ideas on how to test specifically for bad injector cups or head gaskets or narrow down this problem all together with out taking it somewhere i'm not really a fan of other people touching my things.

 

[WarWagon]

Normal to spend about $2000.00 to get a used vehicle into shape.

You know the water pump is bad. It leaks - end of diagnosis. They will seal back up for a short time as I explained above. It also may not be flowing enough coolant to keep the engine cool from a worn impeller and the coolant is boiling over. This is common for a worn pump to show up at idle first. But, so what - it is leaking and needs to be changed. You could have other additional issues at idle. Specifically a bad fan clutch that is not locking up at idle. Possible radiators are plugged with debris.

The cooling system depends on pressure. You taking the cap off when hot or leaving it loose is compounding your problem of keeping coolant in the engine. The coolant that is being pushed out the overflow at 16+ PSI is going to leave the hoses hard. Even when it stops boiling over you could have 14 PSI in the system, but, not enough to pop off the cap. When you cool the engine completely off then and only then does the system pressure go down. Loss of pressure is a problem by a bad water pump, loose cap, etc. After the engine pukes coolant out the overflow - LEAVE IT ALONE!!! It needs to cool down by higher engine RPM etc. Removing the cap to add water will blow a bunch more coolant out of the system that you have to add back in. Unless the low coolant light is on the system level is still fine. Even with the low light on it can still be 'fine' as it is only low not out. The coolant is unknown after the light and could be pouring out the water pump. Likely it is boiling out through the loose cap.

This is simply a different frame of mind to consider. You always have a choice. In this case you appear to be picking where you are going to walk from or be towed from. Figure the cost of overheating your engine and repairing it before you say you don't have a choice of being somewhere. One phone call - 'I am not going to make it." and then take care of your vehicle rather than 'push it' to get somewhere. It's giving you plenty of warning that it has a problem before it really makes you walk after costing you a set of overheated and cracked heads or worse. Hint: Don't idle the truck at this time. I'd park and fix it myself. Rent something to drive in the meantime if you have to. Your cell phone company or AAA is something you should have for a towing service plan of some sort now. Cancel it when you have the kinks worked out.

 

[Achay47]

Yeah, I will admit it wasn't the best choice to drive it but it is what it is. I suppose at this point I will have to get the old beater out of the garage and park the truck for the winter. I will tear into it when I finally get some time off. I was simply looking for simple things to look for or test for to rule out stupid things that could be wrong. Thanks for the help. I'm sure I will learn more then I expected about this motor once I tear it apart, but that's not a bad thing right?

 

[btfarm]

Well you know the water pump is bad so if it were me, I'd replace that and see where you are from there.

Sent from my SCH-I535

 

[WarWagon]

Water pump is a BIG job as it is gear driven and requires the balancer to be pulled off. You might ask the shop you got it from to quote you replacing the pump. They may give you a break.

I like to sub out nasty hard big jobs like ball joints and bushings. (I'd rather pull the engine.) Esp. for a lack of time standpoint. The warranty on labor and parts is nice when the shoddy part gives it up. More common than I like.

 

[btfarm]

Understand the size of the job is big but if it's down in your garage or shop for the winter, then it's worth doing the radiator clean and some other front maint while in there.

 

[Achay47]

All very good points, I will most likely just lay her down for the winter and tear the top half of the block off. New thermostats, water pump, head gaskets, studs, the works... Give me some good experience with this motor and some piece of mind all in one bang. Thanks guys, I'm sure ill encounter some problems along the way I will need help with haha. Looking forward to getting my hands dirty is there anything you guys think should either be replaced or upgraded while I have it apart?

 

[WarWagon]

I suggest you don't fix what ain't broke. I don't see a reason/need to pull the heads. Lots can go wrong and you introduce new failure points. From foreign objects left in the engine to bad or improperly installed gaskets. So you fight the original problem and new problems.

Then there is the time thing. You get the engine pulled down, leave coolant in the cylinders, get busy, and next thing you know you are selling the truck with the heads in the bed to make room for another project or something that RUNS. Kid down the street did this exact thing to a Ford Lightning. Never put it back together. How much do you think he got for the 'some assembly required' truck?

This advice is null and void if you are installing head studs and going to hot rod it even more... Hot rodding is an acceptable use of time and money. :thumbsup:

 

[Pepperidge]

list of things to do...

1. don't buy an LB7 (too late...I know)
2.never buy anyone's hot rod or chipped diesel... you just don't know how it was abused(too late again)
3.While many LB7's did have Head gasket issues, the early 01's were the most prone to failure because GM had a 40 ft lb less torque spec early on that was revised later in 01. so it could still be a head gasket issue.
4.Injectors were replaced...injector cups not being sealed properly are a common problem when LB7 injectors are replaced...even if the cups are pulled and resealed doesn't always guarantee they will seal properly...especially in high hp high boost applications...I had screw in injector cups installed on my heads this last go round...while that gives me some confidence, it still doesn't make me feel all warm and fuzzy becasue LB7 injectors will always have to be replaced...they are a poor design, and whats worse is you now have Industrial Injection crap that will not last long...
5.If I were to be pulling my heads again...for any reason...I'd convert the top end to LBZ heads and injectors...two sets of injectors down the road and the LBZ conversion will have paid for itself...
6.I could say with confidence that the coolant pressurization is one of two things or both...Head gaskets or injector cup sealing issues...with my guess firmly on the cups since the injectors were done recently...

Good luck and stay as far away from industrial injections products as possible next time the truck needs injectors...and it will...

 

[THEFERMANATOR]

list of things to do...

1. don't buy an LB7 (too late...I know)
2.never buy anyone's hot rod or chipped diesel... you just don't know how it was abused(too late again)
3.While many LB7's did have Head gasket issues, the early 01's were the most prone to failure because GM had a 40 ft lb less torque spec early on that was revised later in 01. so it could still be a head gasket issue.
4.Injectors were replaced...injector cups not being sealed properly are a common problem when LB7 injectors are replaced...even if the cups are pulled and resealed doesn't always guarantee they will seal properly...especially in high hp high boost applications...I had screw in injector cups installed on my heads this last go round...while that gives me some confidence, it still doesn't make me feel all warm and fuzzy becasue LB7 injectors will always have to be replaced...they are a poor design, and whats worse is you now have Industrial Injection crap that will not last long...
5.If I were to be pulling my heads again...for any reason...I'd convert the top end to LBZ heads and injectors...two sets of injectors down the road and the LBZ conversion will have paid for itself...
6.I could say with confidence that the coolant pressurization is one of two things or both...Head gaskets or injector cup sealing issues...with my guess firmly on the cups since the injectors were done recently...

Good luck and stay as far away from industrial injections products as possible next time the truck needs injectors...and it will...

I'd say your qualified on the industrial injection opinion with so few miles on your set and they already crapped the bed.

 

[durallymax]

Old thread but I haven't been on much lately.

LB7s are not the worst to own but do have their flaws.

I would've never bought that truck for many reasons, its been modified, the modifications are clearly not well thought out, it was owned by a repair shop, it was leaking coolant.

They must be new to working on Duramaxes or GM vehicles. YOU NEVER and I mean NEVER touch those heater hoses because they WILL break. Just remove the hose at the aluminum hard line and leave the hoses attached to the plastic lines.

If you can see the water pump leaking out of the weep hole (Must be viewed from underneath) then it is bad and needs to be replaced. I did a write up on here how to do it. Takes me a hour, takes a beginner a couple hours, book time is 7 hours.

If you are getting pressure in the cooling system and still loosing some coolant there are only two answers 99% of the time, injector cups or headgaskets. There is no way to determine which one it is but I would lean towards the cups since the injectors were just done. However if you were paying me to do the work I would make you let me do the headgaskets because they are prone to failure anyways and you would be even more pissed if you paid me to dig all the way into it to do the cups and then find out it was the headgaskets and have to tear everything back apart.

Headgaskets are not that hard to do. I see you are in lacrosse, I live 1.5hrs from you and if you do not have a car lift or you are not comfortable doing them yourself you could setup a weekend to bring your truck down here and we can do them. If you are a mechanic you can help and the cost will be much lower. The best way to do headgaskets is to remove the cab which is why you want a lift. This makes the job much faster. Figure 20 hours to do a good job. Book time is 32hrs. They can be done in 15 or so if your screaming. You will reseal the injector cups when you do the headgaskets as well.

If you ever replace injectors in the future only use Bosch remans. If you want larger ones (which you do not need) then get them from exergy.

 

[Pepperidge]

Headgaskets are not that hard to do. I see you are in lacrosse, I live 1.5hrs from you and if you do not have a car lift or you are not comfortable doing them yourself you could setup a weekend to bring your truck down here and we can do them. If you are a mechanic you can help and the cost will be much lower. The best way to do headgaskets is to remove the cab which is why you want a lift. This makes the job much faster. Figure 20 hours to do a good job. Book time is 32hrs. They can be done in 15 or so if your screaming. You will reseal the injector cups when you do the headgaskets as well.

If you ever replace injectors in the future only use Bosch remans. If you want larger ones (which you do not need) then get them from exergy.

Excellent points Vinny...

I wouldn't remove the cab to do the HG's
1. because they can be done without removing the cab (even if adding ARP studs)
2. because I don't have a lift.
3. because even if I had a lift, I have no clue on how to and just how much it entails... other than watching your time lapse video...