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#1 |
chevy truck fan
Join Date: Mar 2005
Location: Gilbert, arizona 85298
Posts: 1,989
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vintage air and overheating issue (LS engine)
hi, I have '86 C10 swb with '13 5.3 gen iv DOD delete LS factory ecm and wiring harness, I installed a gen iv fact. replacement VA A.C. system. my problem is the engine gets too hot with the HCV closed. talking with V.A. and installed the "sometimes recommended" H-PIPE (recommended on "some LS and coyote engines). I am wondering if anyone else had to install a "H-pipe" to adjust for the HCV when closed?
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#2 | |
Registered User
Join Date: Apr 2019
Location: SC
Posts: 74
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Re: vintage air and overheating issue (LS engine)
Quote:
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#3 |
Registered User
Join Date: Sep 2020
Location: Cleveland, Ohio
Posts: 531
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Re: vintage air and overheating issue (LS engine)
I would think it is a good idea. I forget where i read how the coolant flows on an LS engine and you should never plug off the heater hoses. The heater coolant circuit passes over the thermostat to open it. So, the heater ports need a U-hose bypass to allow flow to open the thermostat and cool the engine.
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#4 |
chevy truck fan
Join Date: Mar 2005
Location: Gilbert, arizona 85298
Posts: 1,989
|
Re: vintage air and overheating issue (LS engine)
silver, thanks for the reply, did you use the H-pipe recommended?? or did you make your own? if bought, would you be able to list where purchased or the part no. ?
joyridin, thanks, I learned this as well after VA recommended their "fix". I guess it is not a very "common" issue - just ever so often..... ![]() |
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#5 |
chevy truck fan
Join Date: Mar 2005
Location: Gilbert, arizona 85298
Posts: 1,989
|
Re: vintage air and overheating issue (LS engine)
well I installed the recommended H-pipe as directed by VA and..... no worky!! about 5 minutes after switching the AC on, the temp began to rise & I switched back to the heater when temp got to 240.....
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#6 |
Registered User
Join Date: Sep 2020
Location: Cleveland, Ohio
Posts: 531
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Re: vintage air and overheating issue (LS engine)
Are you sure your fans are coming on when the A/C is engaged or the compressor kicks on? How old is the radiator?
This sounds like more of an issue than the H-pipe. |
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#7 |
chevy truck fan
Join Date: Mar 2005
Location: Gilbert, arizona 85298
Posts: 1,989
|
Re: vintage air and overheating issue (LS engine)
the fans come on per the ECM fact. setting (203degrees) the radiator is brand new alum with fans CFM more than factory for the '13 engine. when the heater switched to heat the engine runs a cool 212-217 degrees, as soon as AC switched (HCV closes) the temp begins to rise (within 5min.). the heating issue began after (while) the VA A.C. install.
thanks |
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#8 |
Registered User
Join Date: Jun 2015
Location: Carlos MN
Posts: 2,042
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Re: vintage air and overheating issue (LS engine)
So what are you running for engine thermostat? Stock? On my stock 20 Silverado with a 6.2 per the temp gauge it runs day in day out at 210 ish. But as soon as I turn on the AC the fans come on and stay on until the AC is off. On my 6.2 LS swapped 80 Camaro I used a 180 degree thermostat. Drilled some 1/8" holes in the flange to get some coolant flow even on startup. Fan set to go on at 205 and off at 195 via the ECM.
The other thing to consider as you are moving the heater hoses on and off you may have created a air block on/in the steam tube. |
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#9 |
Registered User
Join Date: Mar 2020
Location: The Woodlands,Tx
Posts: 575
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Re: vintage air and overheating issue (LS engine)
really a long shot but it happened to me via a bad mechanic. Fans running backwards.
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#10 |
Registered User
Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,699
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Re: vintage air and overheating issue (LS engine)
New Radiator, but is it large enough?? The freon going through the condenser is very hot. Air passes through it first, then through the radiator.. If the ambient air temperature is already above 100 degrees, it is well over that exiting the condenser. Air that hot hitting a radiator that's already too small doesn't offer much cooling effect.
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#11 |
Post Whore
![]() ![]() Join Date: May 2015
Location: Alabama
Posts: 14,637
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Re: vintage air and overheating issue (LS engine)
My 6.0 swap has a 165deg stat in it.. fan1 kicks on at 175, fan2 kicks on at 185
I've never seen mine go over 185..and that's pulling some 10k loads.. You are correct on the H pipe...you don't need to impede the flow to the thermostat or it will run hot Does the H pipe switch to bypass when you turn on AC?
__________________
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#12 |
chevy truck fan
Join Date: Mar 2005
Location: Gilbert, arizona 85298
Posts: 1,989
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Re: vintage air and overheating issue (LS engine)
well I had a shop look at it & it appears that the head gasket might be the issue. there is no indication of a leak into the rad. the engine stays cool until you switch the AC on or under a load (my luck!!) the shop feels the driver's gasket was not installed correctly - fairly easy to install upside down or backwards??? and would still "seal" right, but would block passages and keep from good flow??? so i guess now back to the engine guy for warr. work... aarrggg
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#13 | |
Registered User
Join Date: Apr 2019
Location: SC
Posts: 74
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Re: vintage air and overheating issue (LS engine)
Quote:
I had that issue when I first installed the H pipe. When it was pumping the wrong direction my truck would overheat shortly after switching the AC on. Also, it took several tries to get all the air out of my system…the temps ran high until that was rectified too. My 6.0 runs very cool, even idling in 100 degree weather the temp never goes over 190-200 degrees. |
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#14 |
chevy truck fan
Join Date: Mar 2005
Location: Gilbert, arizona 85298
Posts: 1,989
|
Re: vintage air and overheating issue (LS engine)
thanks for the info. I believe the pump is right (water pump?) after trying the "H-pipe" the issue did not change. the engine guy indicated that the radiator flow test showed to be weak, so he is replacing gaskets to see if fixes????
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#15 |
Registered User
Join Date: Sep 2009
Location: Weare,NH
Posts: 1,592
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Re: vintage air and overheating issue (LS engine)
I used this pressure bypass valve on my Vintage Air setup. It's basically an H-pipe except it's got a spring loaded valve in the middle. When the upstream heater valve is closed the coolant pressure pushes the valve open to bypass.
Four Seasons 74882 Pressure Bypass Open Heater Valve |
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#16 |
chevy truck fan
Join Date: Mar 2005
Location: Gilbert, arizona 85298
Posts: 1,989
|
Re: vintage air and overheating issue (LS engine)
malibu, (and all).... thank you for the replies and suggestions. I took the truck to a "high end shop" and they did some diag on it , they determined that it was for sure mechanical. I took the truck to the engine builder and he agreed to revisit the engine. after his own diagnostics he agreed that it was mechanical, long story short it turned out to be a bad water pump (which was new from engine rebuild) replaced with a new auto store pump and it stays cool!!! now the truck runs at 190-200 with the AC on and in the latest temps ( phx AZ) of 105-112degrees! the history of the engine made it seem like it had to be a different issue than engine related - hence the run around with AC system, it was kinda a perfect storm of multiple things being installed and the temps still on the cooler side (mid 70's at time) so AC was not ran all time and not driving it real far.... this has been a very challenging build, but is starting to show signs of being worth it...
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