Losing pressure with pressure test.

FROM RADIATORS TO THERMOSTATS TO HEATER CORES, IT GOES HERE.

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AstroBum
I am merely driving my van
I am merely driving my van
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Joined: Sun Jan 10, 2016 2:47 pm
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How many wheels are on an Astro van? (4): 4

Losing pressure with pressure test.

Post by AstroBum » Tue Jan 12, 2016 8:30 pm

I have a somewhat new to me 1995 Astro. When I bought it I noticed a weep coming from the drivers side cooling line on the radiator. I replaced the radiator, radiator cap, thermostat, water pump, upper/lower hoses and fluid

I drove it 1200 round trip miles and didn't notice anything strange. The temp gauge always read 160 but blew hot air. A couple days a go the van would not start so I replaced the sprark plugs, wires, cap and rotor and it now runs. I noticed I had a weep out of the radiator cap so I replaced it with a different kind that feels like it seats better. Weep fixed.

After the new radiator cap the temp rose to right below 210 then dove back down to the 160 area.The temp does dance around some. I have attempted to burp the system. Cap off start engine and let idle. Then cap on drive around the block and the filler neck would be empty. I think I'm losing coolant but don't see any. Did a pressure test today and it slowly lost pressure.

Oil dip stick and trans stick look fine. No oil in dex-cool.

Should I remove the fan shroud and double check all the new coolant items I just replaced?

Then compression test each cylinder?

How do I tell the difference between a bad head gasket and a leaking manifold gasket?

I was about to take the van on a long trip so I'm glad these issue came up but damn.

blacknome
I sleep in my van
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Joined: Mon Jun 18, 2007 7:58 pm

Re: Losing pressure with pressure test.

Post by blacknome » Wed Jan 13, 2016 3:20 pm

honestly these van can be a PIA to burp sometimes. When I switched from dex to regular green antifreeze I had to flush the whole system a few times and ended up with a couple air bubbles that took a week or so to burp out. As you probably know when filling the system you need to get the front end as high as you can in the air as the Thermostat is pretty well level with the rad cap. In my case I run it up on car ramps. Fill the system until the thermostat opens. Top it off both in the rad and the overflow. Then let it get to full operating temp with the front and rear heat on. Then let it cool down all while on the ramps. If the system is low it should draw from the overflow. If the system is low your temp needle may move erratically or you may hear the liquid sloshing around in the heater core(s) when you are driving.

As far as the pressure test you should be able to see where its leaking to. Like you stated it will be easier to check everything with the rad shroud off. Pay close attention to the heat diverter valve as they are pretty easy to crack ( I have broken 3 ). If you had it leaking into the engine via either the intake or HG it should show on the plugs and/or exhaust and/or running condition.

Good luck

AstroBum
I am merely driving my van
I am merely driving my van
Posts: 4
Joined: Sun Jan 10, 2016 2:47 pm
antispam: No
How many wheels are on an Astro van? (4): 4

Re: Losing pressure with pressure test.

Post by AstroBum » Wed Jan 13, 2016 8:43 pm

I pressured test my new radiator cap and it was not holding pressure. Brought the rented tester to the store and tested another cap. The tester dropped pressure on all the caps. I even used another pressure tester from the store and I would watch the pressure drop on various caps.

My gut tells me its air in the system. I will continue to try and burp the system. I'm going to go find a steep hill and get the front end up.

AstroBum
I am merely driving my van
I am merely driving my van
Posts: 4
Joined: Sun Jan 10, 2016 2:47 pm
antispam: No
How many wheels are on an Astro van? (4): 4

Re: Losing pressure with pressure test.

Post by AstroBum » Fri Jan 15, 2016 3:20 am

I let it idle for over an hour with the cap off. I got a couple burps but the temp will rise to almost 210 then drop to about 150. Also my lower hose is cold.

I replaced both temp senors.

Took the van for a 40 minutes drive. Temp stays around 150 then will climb almost to 210 then drop back down. It does this once ever 20 minutes.

I put in a new AcDelco thermostat with the other parts. I installed it with the spring facing the block. Also looking online most pictures show the thermostat sitting on the top of the block. Mine goes on the front. This is a 1995 van.

Going to try and burp some more but maybe my new thermostat is bad.

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