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max57

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Dec 12, 2014
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Upstate, NY
I get these good ones guys. I left the house this morning, checked all fluids, water full, engine 160 degrees i drove 15 miles without doing over 3/4 throttle and it stayed around 160-170 mark,Thermostat temp. As soon as i do WOT my temp gauge goes to 110 then comes back up , and climbs fast to 180 like it gets a shot of air on sensor . and a little higher each time I lay into it. So I removed the cap (carefully) and run it , all is fine til I lay into it WOT and then it pushes water out over the top. as soon as I let off water returns right back down. (in Video) . It has a ELECTRIC water pump and none in engine so flow is always moving the same speed. so not pushing out from RPM's..
I put pressure gauge on Rad and run it easy , all Good. Hard, a Couple times I had it raised to 10 psi ONLY WOT, then it lowered right back down within a few seconds as I keep driving. Like it is crankcase pressure??? Cracked Head??? I can run it 3/4 throttle all day and nothing , Only WOT. I put 20psi on it and seem to hold it pretty good. What shall I do to troubleshoot it farther.
the funny thing is my Old engine pushed water out , i auto thought it was blown head gasket cause it did not have head studs. But Maybe NOT.
https://youtu.be/zNanyCvp_Io
NEW BUILD:
Wagler street rods
.020 mahle pistons cast 16.5 .075 pockets
40% ported heads
all ARP studs
Wagler dual spring
Wagler pushrods
Socal alt Fire cam 3388
S480 over 366 super/.74 Turbos
Lincoln 60% injectors
ATS twin cp3
Tuned by Rob
4L80E Rossler Trans
Pro torque Convertor
 

ZeroGravity58

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Mar 23, 2008
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Double post, duplicate post located here (https://www.duramaxdiesels.com/forum/showthread.php?t=82617)





You say it didn't have studs but your post/parts list says it has studs, are you saying you tore it down because you thought it had a blown gasket and it originally didn't have studs? Do a pressure test of the cooling system for a few hours and see what happens.

What he is saying is his old motor that did not have studs is doing the same thing as the new motor with studs. He thought the old motor had a blown head gaskets
 

Bdsankey

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What he is saying is his old motor that did not have studs is doing the same thing as the new motor with studs. He thought the old motor had a blown head gaskets

Thats what I am understanding as well but clarity is invaluable. Cooling system pressure test and go from there.
 

ZeroGravity58

Well-known member
Mar 23, 2008
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Thats what I am understanding as well but clarity is invaluable. Cooling system pressure test and go from there.

I would test it to make sure. I've run into problems with electric water pumps in gas drag racing motors but never used one in a diesel. What I learned is if the pump does not flow enough OR if there is no restrictor and the water moves to fast you can actually get hotspots around the cylinders and the water can start to boil. I had problems like you are talking about and had to switch out to a bigger pump and smaller restrictor.
 

Bdsankey

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I'm betting its flash boiling in the heads. For example, the boiling point fluids is determined by the fluid properties/pressure/temperature. Gale Banks stated on his last "breaking a duramax" video that they are observing ~80-90psi of coolant pressure before the thermostats/in the heads. While this info (I believe) was taken from an L5P it is not a bad assumption to assume the earlier trucks run a fair bit of pressure as well as flow. This would raise the boiling point of the coolant and thus help it resist boiling. Also, I believe Banks states they needed to upgrade their flow meter as it was maxed out at 100gpm by ~3400-3600rpm engine speed.
 

DAVe3283

Heavy & Slow
Sep 3, 2009
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Like people are saying, pressure test your cooling system. If your cooling system holds pressure, you can try a reverse pressure test. That is how I found my cracked heads.

  • Vehicle stone cold. This is important or you get false results.
  • Put the pressure test gauge on the cooling system, but leave at 0 PSI.
  • Put a boost leak check adapter on your intake (anywhere in the intake system, we aren't looking for leaks in the tubing). I usually put it straight on the y-bridge.
  • Put 10-20 PSI regulated air into the intake. You can do more, but risk having the boost leak adapter pop off and smack you in the face. Hypothetically :roflmao:
  • Watch for any pressure increase in the coolant. It should stay at 0 (not 1, not 1/2, ZERO) forever. I leave the air pressure on for 5+ minutes to be sure.
If you don't see pressure come in from the intake, you can do the same test with the exhaust. Don't worry about air leaking out of exhaust joints, you only care if some of that air ends up in the coolant.

If all that passes, then it could be what ZeroGravity58 says, and be coolant flash boiling in the heads. Though from your video, you didn't seem to be making a ton of power before it started pushing coolant, so I am not sure it is flash boiling. If it was only at full power, then sure, but since you were just brake boosting it a bit, I wouldn't think that's enough power/heat to flash boil that much coolant. Sure looked like air being pushed through, and lots of it.
 

max57

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Dec 12, 2014
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Upstate, NY
I did the video when engine was Cooler,(seems to be worse cold now that you mention it) then pressure tested Hot. It Held pressure Hot. I will try cold engine today as you say. Yes while I was in deep thought last night I was thinking it could be normal, (flash heating).
The car does not Overheat at the Radiator , gets to 210 and fan kicks on. But Temp gauge (in Engine) will go from 160 down to 110 then fly up to 180 on a cool boost, Hot it just rises 30 degrees in 15 seconds and fan will kick on when rad starts to get warm. So just got to see if flash heat or blown gasket.
Old motor did it ever since I put the 60 injectors in it and the twins and Race tune also. It had a normal water pump for 2 days till twisted shaft off so I put the electric pump on it First. It did this same thing and I automatically condemned it to be a head gasket.
Does any of you guys trucks with twins and bigger fuel Temperature climb by 30-40 degres when you boost her for 10 seconds???
 
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Bdsankey

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I did the video Cooler Engine,(seems to be worse cold now that you mention it) then pressure tested Hot. It Held pressure Hot. I will try cold engine today as you say. Yes while I was in deep thought last night I was thinking it could be normal, (flash heating).
The car does not Overheat at the Radiator , gets to 210 and fan kicks on. But Temp gauge (in Engine) will go from 160 down to 110 then fly up to 180 on a cool boost, Hot it just rises 30 degrees in 15 seconds and fan will kick on when rad starts to get warm. So just got to see if flash heat or blown gasket.
Old motor did it ever since I put the 60 injectors in it and the twins and Race tune also. It had a normal water pump for 2 days till twisted shaft off so I put the electric pump on it First. It did this same thing and I automatically condemned it to be a head gasket.
Does any of you guys trucks with twins and bigger fuel Temperature climb by 30-40 degres when you boost her for 10 seconds???

My temps do not rise that fast. I have a S480/96/T6 single with 250s, dual pumps etc (truck in sig).
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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I did the video Cooler Engine,(seems to be worse cold now that you mention it) then pressure tested Hot. It Held pressure Hot. I will try cold engine today as you say. Yes while I was in deep thought last night I was thinking it could be normal, (flash heating).
The car does not Overheat at the Radiator , gets to 210 and fan kicks on. But Temp gauge (in Engine) will go from 160 down to 110 then fly up to 180 on a cool boost, Hot it just rises 30 degrees in 15 seconds and fan will kick on when rad starts to get warm. So just got to see if flash heat or blown gasket.
Old motor did it ever since I put the 60 injectors in it and the twins and Race tune also. It had a normal water pump for 2 days till twisted shaft off so I put the electric pump on it First. It did this same thing and I automatically condemned it to be a head gasket.
Does any of you guys trucks with twins and bigger fuel Temperature climb by 30-40 degres when you boost her for 10 seconds???

nope, not even our race cummins does this with an electric pump on the front and a helper pump at the rad in the back.
 

max57

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Dec 12, 2014
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Upstate, NY
Did a pressure test on Intake side 30Lbs @ 30 minutes and nothing. Have to do exhaust side now but>>>
It is starting to make sense it is flashing, fast when cold as there is not much water flow though block because of bypass tube until the thermostats open. I think I will try putting a $850 billet pump (is there another option) , in the normal spot in block and leave electric and make sure it is warmed enough to have both thermostats open (160) before getting rough on it. Any other water pump options that will not break. ?? My Stewart is rated 55 GpM which probably needs a little help.
 
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DAVe3283

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Sep 3, 2009
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Did a pressure test on Intake side 30Lbs @ 30 minutes and nothing. Have to do exhaust side now but>>>
It is starting to make sense it is flashing, fast when cold as there is not much water flow though block because of bypass tube until the thermostats open. I think I will try putting a $850 billet pump (is there another option) , in the normal spot in block and leave electric and make sure it is warmed enough to have both thermostats open (160) before getting rough on it. Any other water pump options that will not break. ??
If it turns out to be flash boiling, you can go to a bigger electric pump to get some pressure in the block, or go back to a mechanical water pump. Do you have any kind of restrictor besides the thermostats? How is your bypass setup?

Most people are able to make a mechanical pump work. What kind of RPMs are you turning? I spin 4,800 RPM periodically and run a stock pump that has been pinned. If you turn more than that, you can clip the impeller down some to help. It seems that pinning the pump is more reliable than welding them, as the welds seem to fail at a higher rate.

Seeing the leak more when cold kind of goes against the flash boiling theory, as the coolant should be under more pressure when cold due to the lack of flow. Unless your pump doesn't make head pressure for crap. Really, we need some details on the exact pump and routing you are running.
 

Bdsankey

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Did a pressure test on Intake side 30Lbs @ 30 minutes and nothing. Have to do exhaust side now but>>>
It is starting to make sense it is flashing, fast when cold as there is not much water flow though block because of bypass tube until the thermostats open. I think I will try putting a $850 billet pump (is there another option) , in the normal spot in block and leave electric and make sure it is warmed enough to have both thermostats open (160) before getting rough on it.

DHD high rpm water pump and SoCal pressure relief kit.



If it turns out to be flash boiling, you can go to a bigger electric pump to get some pressure in the block, or go back to a mechanical water pump. Do you have any kind of restrictor besides the thermostats? How is your bypass setup?

Most people are able to make a mechanical pump work. What kind of RPMs are you turning? I spin 4,800 RPM periodically and run a stock pump that has been pinned. If you turn more than that, you can clip the impeller down some to help. It seems that pinning the pump is more reliable than welding them, as the welds seem to fail at a higher rate.

My DHD high rpm plastic pump (LLY) seems to be holding up fine after 2 seasons of repeated 4800-5200rpm without any pressure relief system.
 

max57

Member
Dec 12, 2014
117
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Upstate, NY
DHD high rpm water pump and SoCal pressure relief kit.

I do not see a high RPM pump for LBZ


Most people are able to make a mechanical pump work. What kind of RPMs are you turning?
Im only doing around 4000 rpm and had welded break. Does anyone have a releif for them now.?
 

Bdsankey

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DHD high rpm water pump and SoCal pressure relief kit.

I do not see a high RPM pump for LBZ


Most people are able to make a mechanical pump work. What kind of RPMs are you turning?
Im only doing around 4000 rpm and had welded break. Does anyone have a releif for them now.?

Use an ACDelco plastic pump. The DHD high rpm pump is based for the LB7 & LLY where they modify an LBZ/LMM pump housing to accept the larger LB7 & LLY lower rad hose. The best solution is a plastic impeller pump and coolant relief from SoCal IMO.
 

max57

Member
Dec 12, 2014
117
0
16
Upstate, NY
Right now I just took guts out of water pump and frost plugged shaft port. Cut lower hose and installed Stewart electric water pump. Mitsu Low temp thermostats. all original bypass. I never heard of this craziness so all a learning curve for me.
 

coker6365

Coker6303's ***** Daddy
Dec 4, 2011
486
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18
After rolling through several pumps on my LBZ at high rpms, the SoCal Bypass appears to have cured my water pump R&R practice. Stock AC Delco with a welded drive gear is holding up great.
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gmduramax

Shits broke
Jun 12, 2008
4,045
226
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Nor cal
Right now I just took guts out of water pump and frost plugged shaft port. Cut lower hose and installed Stewart electric water pump. Mitsu Low temp thermostats. all original bypass. I never heard of this craziness so all a learning curve for me.

Mishimoto stats? If so pull those out and find something better. They take so long to open.