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Cooling system pressure help needed

Could it have the wrong water pump on it now? (standard vs reverse rotation)

Was any work done prior to this pressure building problem or was this a long running, issue free truck?
 
My understanding from what I've heard with the wrong water pump is that the truck will overheat. The OP seems to indicate the truck doesn't even get warm before it starts to blow things.?
 
dyeager535 said:
There is no reason a 13 or even 16PSI cap should have you blowing radiators or heater cores up. That's essentially standard pressure nowadays, the cap is what vents the pressure above its rating, period.

Where did the new radiator leak? If this is an abused system, its entirely possible all the hoses, the heater core, and the radiator needed to be replaced. With new radiators, if it is plastic tanked, those will leak out of the tank to core joint fairly commonly.
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Right! Everything but water pump has been done, and still issues. That's why it's so puzzling.
It's not a plastic rad tank, metal. Leaked out of bottom of the side tank, on a seam.
Had a great radiator shop tear it open and weld up the entire seam.
It just keeps building pressure until it finds a weak leak.
 
Again, radiator system pressure check and compression test. When you do the compression check, monitor the pressure at the radiator.
 
nvrenuf said:
Could it have the wrong water pump on it now? (standard vs reverse rotation)

Was any work done prior to this pressure building problem or was this a long running, issue free truck?
Click to expand...

dyeager535 said:
My understanding from what I've heard with the wrong water pump is that the truck will overheat. The OP seems to indicate the truck doesn't even get warm before it starts to blow things.?
Click to expand...

Still has the same water pump from when I bought it. This was essentially a one owner truck its whole life, and the original owner was a GM mechanic. Doubtful he monkied up the water pump. Water flows in the right direction, plus the first 9 months or so I had it, no issues. It spent pretty much its entire life with light driving, and I've been DD'ing it(hense the increased rate of issues & part failures).

I'm gonna clean out this overflow line and rez, as there have been some chunks of stuff in the Rez, plus blowing into the radiator there's a bit of back pressure before it blows thru to the Rez. There could very well be some sort of debris/gasket material/etc somewhere in there that's not letting it overflow.
Next step after that is pressure check system.


Thank you guys so much for the help, I really do appreciate it. We've been rerunning through everything as y'all post.
Keep it coming If y'all think of any thing else.
 
Also, we jump wired pins A& B and read the codes-
Code 45 was the only thing that popped up. (Oxygen sensor circuit, rich exhaust indicated). Seems doubtful that could have anything to do with coolant system pressure though, correct?
 
I've seen engines with a head gasket leak pressurize the cooling system and not let any water get in the crankcase or smoke come from the tail pipe more than once..

One car was a Buick with a 350 Buick engine--I sold the guy a new upper hose and he called a few hours later to say the hose "blew apart",I told him it was very unlikely the hose was at fault,but my boss said go bring him another one,he's good customer and I want to keep him happy..

I delivered it,and waited for him to pull off the blown up hose and put the new one on--he started it up and I watched the upper hose grow larger like a balloon until it was the size of a football,I screamed "SHUT IT OFF !"....you could hear water boiling in the hose,he had replaced the thermostat just before the first hose went on and we assumed it was still good...his father came over and said "I told you it needs a head gasket--kid never listens to me!"..

Next day the kid brought the cylinder heads in to be shaved and to buy a head set for it..he showed me the bad gasket,it had only one small 1/4" spot rusted away around a coolant passage ...you could see the trail the combustion gases made from the rusted spot to the coolant passage in the head..
I was kind of surprised the radiator cap didn't blow off the excess pressure first though,but engines do weird things sometimes..
The engine ran good again once the new gaskets were put on--we did a quick valve lapping to all the valves while it was apart too..
 
diesel4me said:
I've seen engines with a head gasket leak pressurize the cooling system and not let any water get in the crankcase or smoke come from the tail pipe more than once..

One car was a Buick with a 350 Buick engine--I sold the guy a new upper hose and he called a few hours later to say the hose "blew apart",I told him it was very unlikely the hose was at fault,but my boss said go bring him another one,he's good customer and I want to keep him happy..

I delivered it,and waited for him to pull off the blown up hose and put the new one on--he started it up and I watched the upper hose grow larger like a balloon until it was the size of a football,I screamed "SHUT IT OFF !"....you could hear water boiling in the hose,he had replaced the thermostat just before the first hose went on and we assumed it was still good...his father came over and said "I told you it needs a head gasket--kid never listens to me!"..

Next day the kid brought the cylinder heads in to be shaved and to buy a head set for it..he showed me the bad gasket,it had only one small 1/4" spot rusted away around a coolant passage ...you could see the trail the combustion gases made from the rusted spot to the coolant passage in the head..
I was kind of surprised the radiator cap didn't blow off the excess pressure first though,but engines do weird things sometimes..
The engine ran good again once the new gaskets were put on--we did a quick valve lapping to all the valves while it was apart too..
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They already checked with the fluid that detects combustion gas.
I asked about it and he responded with what the mechanics checked
 
What @diesel4me is saying is completely possible as combustion pressure is higher than cooling system pressure. Pressure then only goes one way. Common? Maybe not, possible? I think definitely.
 
6872xtc said:
What @diesel4me is saying is completely possible as combustion pressure is higher than cooling system pressure. Pressure then only goes one way. Common? Maybe not, possible? I think definitely.
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If that were the case, with the cap off, wouldn't you see some massive surge of coolant or something, combined with bubbles/hydrocarbons/exhaust gas? I'm asking, I don't know for sure, would seem that there would be some other symptoms exhibited if it was pumping that much of a gas into the coolant?

I have to assume that even one cylinders worth of volume is enough to overwhelm the vent line/radiator cap however, so that definitely seems plausible.
 
Yep, that was why I made the suggestion. With that much gas it should show up with the cap off.
But, the combustion gas tester should have shown a massive reaction.

I'm still leaning toward some kind of blockage at the cap/overflow tube area.
Of course, I suppose someone could have plumbed the AC compressor output into the cooling system............
 
dyeager535 said:
If that were the case, with the cap off, wouldn't you see some massive surge of coolant or something, combined with bubbles/hydrocarbons/exhaust gas? I'm asking, I don't know for sure, would seem that there would be some other symptoms exhibited if it was pumping that much of a gas into the coolant?

I have to assume that even one cylinders worth of volume is enough to overwhelm the vent line/radiator cap however, so that definitely seems plausible.
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Yes, I believe that you are correct. I didn't think through this correctly.
Sorry.
 
I don't know if there would be a massive surge of gasses, however.

Case on point is my '72 K5 which I could smell coolant in the exhaust, occasionally after starting it hot. It still ran to Moab, wheeled for 3 days, and then home. Only went through 2+ quarts of coolant. It did have signs of coolant leaking into 2 cylinders, but never gushed coolant.
I didn't check the coolant for exhaust gas with the chemical.
 
Says he has already had it checked chemically for exhaust gases in coolant.
 
I might be qualified to comment on this based on all the drama I went thru with the vortec 350 in Ned.....Are you leaking steam or fluid when it over pressures and blows something? If your getting mostly steam, then your getting an air pocket in the motor that's stopping the water flow and heating up/expanding till until it blows something. I was getting insane pressures that literally blew hoses off at one point. We thought it was a head gasket but had no smell, no water in exhaust, plugs were fine ect...The air pocket in the motor never would get pushed out when refilling the system but it acted like its full of water. The pocket is gonna start on the firewall side of the drivers side head. and any air in the system is gonna get pushed right to their and never get out if other things are amiss.

My problems were these in no order and they all contributed and made figuring it all out a nightmare.....

wrong water pump. did a serp belt conversion and got a standard rotation water pump unintentionally when we thought it was a reverse roation. They look exactly the same from the outside

A brand new thermostat that was bad and not opening when it should have.

No short heater hose connecting the water pump to the FRONT of the intake manifold. There needs to be a hose there to circulate the water in the intake/heads before the thermostat opens up. (in the picture the hose goes from the front orange plug to the water pump) you cant bipass that plug and connect ir directly to the heater hose from the water pump. (thats what I did) water needs to go out of the back of the water pump, into the intake, out of the intake into the heater hose.

I had a heater hose connected to the wrong radiator hose which caused the water to dead end in my propane mixer (which hooks up just like a heater core does) instead of flow thru. So when you say heater core is bypassed is that with both hoses connected to a pipe? or did you block off the hoses..cause if they are blocked your not getting the flow thru the manifold you need to stop hot spots and push out the air bubbles.

I have a rear mounted radiator, which you probably dont, which is good.

What I would do is the this...pull the thermostat out. check the small heater hose to the water pump to make sure its not blocked with rust or some other crap. connect the heater hoses together with piece of tube. either pull the water temp sender in the manifold or pull off the top radiator hose to the thermostat cover (or do both). stick a hose in top radiator and backfill water till i had water coming out the temp sender and the top of the thermostat housing. Squeeze the lower hose to make sure you dont have a bubble sitting down there. Then tighten stuff up while it continued to backfill water once your super sure you got all the air out. Then run it and see what happens. Also remember hoses go soft and collapse in a vacuum so look for a hose doing that too. If it works, then great its an air bubble and you figured it out. Throw the thermostat in and do it again. If if still over pressures I'd throw that new water pump on next.

If it still doesnt work right..Then I would fly Chris Perry to my house, give him a beer and have him stare at my engine for 40 minutes. Cause thats ultimately how mine got figured out.

tbi.jpeg

tbi.jpg
 
Factory TBI doesn't have that hose. Coolant for the heater comes off of the passenger rear of the intake manifold, and the 2 '90s here return to the radiator. My '95 returns to that port on the water pump.
 
Blazooki said:
I might be qualified to comment on this based on all the drama I went thru with the vortec 350 in Ned.....Are you leaking steam or fluid when it over pressures and blows something? If your getting mostly steam, then your getting an air pocket in the motor that's stopping the water flow and heating up/expanding till until it blows something. I was getting insane pressures that literally blew hoses off at one point. We thought it was a head gasket but had no smell, no water in exhaust, plugs were fine ect...The air pocket in the motor never would get pushed out when refilling the system but it acted like its full of water. The pocket is gonna start on the firewall side of the drivers side head. and any air in the system is gonna get pushed right to their and never get out if other things are amiss.

My problems were these in no order and they all contributed and made figuring it all out a nightmare.....

wrong water pump. did a serp belt conversion and got a standard rotation water pump unintentionally when we thought it was a reverse roation. They look exactly the same from the outside

A brand new thermostat that was bad and not opening when it should have.

No short heater hose connecting the water pump to the FRONT of the intake manifold. There needs to be a hose there to circulate the water in the intake/heads before the thermostat opens up. (in the picture the hose goes from the front orange plug to the water pump) you cant bipass that plug and connect ir directly to the heater hose from the water pump. (thats what I did) water needs to go out of the back of the water pump, into the intake, out of the intake into the heater hose.

I had a heater hose connected to the wrong radiator hose which caused the water to dead end in my propane mixer (which hooks up just like a heater core does) instead of flow thru. So when you say heater core is bypassed is that with both hoses connected to a pipe? or did you block off the hoses..cause if they are blocked your not getting the flow thru the manifold you need to stop hot spots and push out the air bubbles.

I have a rear mounted radiator, which you probably dont, which is good.

What I would do is the this...pull the thermostat out. check the small heater hose to the water pump to make sure its not blocked with rust or some other crap. connect the heater hoses together with piece of tube. either pull the water temp sender in the manifold or pull off the top radiator hose to the thermostat cover (or do both). stick a hose in top radiator and backfill water till i had water coming out the temp sender and the top of the thermostat housing. Squeeze the lower hose to make sure you dont have a bubble sitting down there. Then tighten stuff up while it continued to backfill water once your super sure you got all the air out. Then run it and see what happens. Also remember hoses go soft and collapse in a vacuum so look for a hose doing that too. If it works, then great its an air bubble and you figured it out. Throw the thermostat in and do it again. If if still over pressures I'd throw that new water pump on next.

If it still doesnt work right..Then I would fly Chris Perry to my house, give him a beer and have him stare at my engine for 40 minutes. Cause thats ultimately how mine got figured out.

View attachment 258594

View attachment 258595
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You make me sound creepy. I kinda like it.
 
I was going for more like the horse whisperer but for engines
 
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