[DeTomaso] Overheating problem

[George Sekula]

Thank you all for your help. Dozens of attempts, three times I could idle for 30 minutes without an excursion, then 10 minutes on the highway and the temperature climbs.  Drained oil and found no contamination.  No smoke out the tailpipe.  No little air bubble, just volcano like eruptions.  Did a combustion-gas-in-coolant test four times with no combustion gas detected.  When I did a cylinder leak down test on cylinder 3, pointer was in the red and coolant was overflowing the pressure tank.  I have some work to do, hoping it is just the head gasket.
________________________________
From: Mike Drew <mikeldrew at aol.com>
Sent: Monday, July 1, 2024 5:05 PM
To: George Sekula <georgesekula at outlook.com>
Cc: detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
Subject: Re: [DeTomaso] Overheating problem

George,

The symptoms you describe are consistent with a lot of trapped air in the system. Filling and bleeding the system is normally an iterative process that can take several days (for complete cooldown between bleeds).

With the radiator bleeder open, and the rear of the car elevated, the pressure tank should be filled while the engine is running. When the thermostat opens it will gulp water from the tank, practically emptying it, at which point you should top it off.

This will make a big fat mess.

Bleeding the air from the bleeder and topping off the tank after the thermostat has opened will enable you to get it mostly full. Then install a new cap on the pressure tank and ensure the overflow is about half full.

When the car cools off it may suck water from the overflow so the pressure tank remains full but the overflow level is reduced. If your cap is leaking it will just suck air, so the pressure tank level will be down and the overflow will remain the same.

After a few cycles it should resolve itself.

As a technique I sometimes overfill the overflow bottle, knowing that it will dump excess coolant overboard. Route a long hose from the overflow to the rear of the car so it doesn’t get onto the tire.

It will dump upon engine shutdown. This can be embarrassing but eventually it will reach its happy spot and stop dumping.

Good luck and please keep us posted!

Mike


Sent from my iPad

> On Jul 1, 2024, at 13:35, George Sekula <georgesekula at outlook.com> wrote:
>
>    I am struggling with overheating after I changed the water pump and
>   thermostat.  New water pump is an Edelbrock 8844 with a new overdrive
>   pully.  The thermostat is a Robertshaw 333 from Flowkooler via Summit
>   Racing. I tested the operating temperature on the thermostat several
>   times and it opens at exactly at180F.  The dimensions match their
>   website.  The original bypass restrictor is still installed, with a
>   3/4" hole; the thermostat plunger is 11/16".  It acts like there is
>   water in the engine that does not get circulated until you shut the
>   engine off.  Hot water violently flows into the overflow tank and the
>   water temperature instantly raises 30F.  When you start the engine
>   everything acts normal.  You can feel the water start to flow in the
>   tube at 180F, radiator warms up, fans turn on and the temperature holds
>   perfect for a while.  Then the temperature slowly climbs.  Driving the
>   car, the temperature will slowly climb higher, maybe 210F. The two
>   radiator fan temperature switches work as they should, but they are not
>   detecting this hot water.  When I filled the system, the bleeder on top
>   of the radiator was open with 3 ft of clear tubing to get it higher
>   than the block and tanks.  The temperature sender in the top of the
>   block was removed until coolant flowed out (wish I had added tubing).
>   Tried raising the back, then tried raising the front while topping off
>   the tank. The leaking pump that I replaced was a Wieland and it was not
>   drilled for the bypass circuit, the thermostat was a Gates 180 that I
>   installed 30 years ago. Radiator is a 3-pass aluminum with two large
>   pusher fans.  What is the best method for filling the system to prevent
>   trapped air?  Are there other things that I need to check?
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>
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-------------- next part --------------
   Thank you all for your help. Dozens of attempts, three times I could
   idle for 30 minutes without an excursion, then 10 minutes on the
   highway and the temperature climbs.  Drained oil and found no
   contamination.  No smoke out the tailpipe.  No little air bubble, just
   volcano like eruptions.  Did a combustion-gas-in-coolant test four
   times with no combustion gas detected.  When I did a cylinder leak down
   test on cylinder 3, pointer was in the red and coolant was overflowing
   the pressure tank.  I have some work to do, hoping it is just the head
   gasket.
     __________________________________________________________________

   From: Mike Drew <mikeldrew at aol.com>
   Sent: Monday, July 1, 2024 5:05 PM
   To: George Sekula <georgesekula at outlook.com>
   Cc: detomaso at server.detomasolist.com <detomaso at server.detomasolist.com>
   Subject: Re: [DeTomaso] Overheating problem

   George,
   The symptoms you describe are consistent with a lot of trapped air in
   the system. Filling and bleeding the system is normally an iterative
   process that can take several days (for complete cooldown between
   bleeds).
   With the radiator bleeder open, and the rear of the car elevated, the
   pressure tank should be filled while the engine is running. When the
   thermostat opens it will gulp water from the tank, practically emptying
   it, at which point you should top it off.
   This will make a big fat mess.
   Bleeding the air from the bleeder and topping off the tank after the
   thermostat has opened will enable you to get it mostly full. Then
   install a new cap on the pressure tank and ensure the overflow is about
   half full.
   When the car cools off it may suck water from the overflow so the
   pressure tank remains full but the overflow level is reduced. If your
   cap is leaking it will just suck air, so the pressure tank level will
   be down and the overflow will remain the same.
   After a few cycles it should resolve itself.
   As a technique I sometimes overfill the overflow bottle, knowing that
   it will dump excess coolant overboard. Route a long hose from the
   overflow to the rear of the car so it doesn't get onto the tire.
   It will dump upon engine shutdown. This can be embarrassing but
   eventually it will reach its happy spot and stop dumping.
   Good luck and please keep us posted!
   Mike
   Sent from my iPad
   > On Jul 1, 2024, at 13:35, George Sekula <georgesekula at outlook.com>
   wrote:
   >
   >    I am struggling with overheating after I changed the water pump
   and
   >   thermostat.  New water pump is an Edelbrock 8844 with a new
   overdrive
   >   pully.  The thermostat is a Robertshaw 333 from Flowkooler via
   Summit
   >   Racing. I tested the operating temperature on the thermostat
   several
   >   times and it opens at exactly at180F.  The dimensions match their
   >   website.  The original bypass restrictor is still installed, with a
   >   3/4" hole; the thermostat plunger is 11/16".  It acts like there is
   >   water in the engine that does not get circulated until you shut the
   >   engine off.  Hot water violently flows into the overflow tank and
   the
   >   water temperature instantly raises 30F.  When you start the engine
   >   everything acts normal.  You can feel the water start to flow in
   the
   >   tube at 180F, radiator warms up, fans turn on and the temperature
   holds
   >   perfect for a while.  Then the temperature slowly climbs.  Driving
   the
   >   car, the temperature will slowly climb higher, maybe 210F. The two
   >   radiator fan temperature switches work as they should, but they are
   not
   >   detecting this hot water.  When I filled the system, the bleeder on
   top
   >   of the radiator was open with 3 ft of clear tubing to get it higher
   >   than the block and tanks.  The temperature sender in the top of the
   >   block was removed until coolant flowed out (wish I had added
   tubing).
   >   Tried raising the back, then tried raising the front while topping
   off
   >   the tank. The leaking pump that I replaced was a Wieland and it was
   not
   >   drilled for the bypass circuit, the thermostat was a Gates 180 that
   I
   >   installed 30 years ago. Radiator is a 3-pass aluminum with two
   large
   >   pusher fans.  What is the best method for filling the system to
   prevent
   >   trapped air?  Are there other things that I need to check?
   > _______________________________________________
   >
   >
   > Detomaso Email List is not managed by POCA
   > Posted emails must not exceed 1.5 Megabytes
   > DeTomaso mailing list
   > DeTomaso at server.detomasolist.com
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