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1995 Astro van 4.3 vortech over heat help needed

Posted by linda99508 (My Page) on
Thu, Oct 8, 09 at 22:19

My van started to over heat last week. I had a guy down the street work on it for me..... He replaced the thermostat,waterpump,fan and even changed the head gaskets.
It is still over heating and now it seems to of lost some power also.... What else can it be if all those things have been replaced??? The top radiator hose gets hard as a rock when it hits the red mark but the bottom hose does not buid pressure like the top hose.... Could it be a bad thermostat??? And what about the loss of power now???Could it just be from over heating as he said??? Thanks in advance for any help on my van.


Follow-Up Postings:

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RE: 1995 Astro van 4.3 vortech over heat help needed

Update: Forgot to mention replaced radiator because the first one split right down the side completely. This is when all the trouble started. What we found out by accident today was when we changed the hoses and the rad cap it still over heated and top hose built with pressure again when the water started to boil. My hand touched top of radiator and it was hot hot hot. But when I touched the radiator 5 inches below from top. It was cold. Cold the whole way to the bottom. It was like only the top 5 inches was working to cool the motor. Could I have gotten a bad radiator? This was an aftermarket aluminum rad. So tomorro I am taking it to be tested and see what is what. But the first one ripped apart from to much pressure that caused everything to be reoplaced.


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RE: 1995 Astro van 4.3 vortech over heat help needed

The top of the rad being very hot, but getting cold within the first 5 inches tells me you have little to no coolant flow. Was this a shop you took your car too or not?

One not to uncommon mistake that the person doing the work could have done is he may have accidentally installed the thermostat backwards, or it could simply be defective. The thermostats job is to control the coolant flow through the radiator once the engine reaches a minimum temperature.

Another not so common but potential issue could be that the wrong pump was used and its impeller is being spun backwards. Some pumps are driven clockwise, and some are counter-clockwise depending on how the belt runs the pump. Parts suppliers today are much better about not making this mistake which a mechanic would not easily catch because the impeller isn't always visible.

Lastly, the head gaskets were replaced, but were the heads sent out to be tested by a machinist while they were off? The original failure could have caused one or both of the heads to crack or warp, and they might have needed to be replaced. If they have simply warped, they should have been machined back flat while they were off. (which actually requires a valve job too) Either way, cracked or warped you may still be getting combustion gasses into the cooling system and that can be preventing proper coolant flow through the radiator.


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RE: 1995 Astro van 4.3 vortech over heat help needed

Everything was done correctly from head gaskets to the correct water pump. The hesitation was from heating up. The problem was the radiator. The bottom cores was plugged up. Replaced with another one and problem solved. Here the radiator was not purchased new,but was from a junkyard. Here is what was said to happened.

You ever heard of not mixing green antifreeze with orange?
Well I never heard that before and that is what the radiator got clogged. They said the radiator from the donar vehicle had orange coolant added to green or vice versa and cause the sludge mush like clog in the bottom half of the rad. I never heard of this before and was curious if any one else heard of it.

I also heard of all those things you mentioned john from backwards spinning water pumps to installing the thermostat in backwards. We are not strangers to the mechanics world. Just never had a clogged radiator before that caused this much trouble.


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RE: 1995 Astro van 4.3 vortech over heat help needed

The clogging in the bottom of the first used replacement radiator was likely caused by the original owners neglect of the cooling system. Dexcool when maintained correctly does an excellent job and indeed lasts five years and seriously, over 100,000 miles without causing problems. But if there is a system leak that is never dealt with, then air constantly enters the system and the coolant breaks down into a powdery sludge. Remember this isn't the coolants fault, its neglect and not ensuring that the vehicle is serviced correctly. People placing the blame on intermixed coolants is simply based on the misunderstanding that the sludge was the result of differing coolants, instead of the fact that the reason coolant was being added was because of the system leaking. You can add regular coolant to Dexcool, its just doing so makes it no longer extended life coolant and then it should be replaced completely every two years.

Quote "I also heard of all those things you mentioned john from backwards spinning water pumps to installing the thermostat in backwards. We are not strangers to the mechanics world. Just never had a clogged radiator before that caused this much trouble."

You installed a used radiator and assumed it was like new. Tell me again how "We are not strangers to the mechanics world"


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RE: 1995 Astro van 4.3 vortech over heat help needed

Guess you never used remanufactured parts there John. They are a bit cheaper than new. I bet you never tore 3 or 4 engines apart and used bits and pieces from them all to make one good one. that includes no machine work to crank or rods and used std bearings and not have a problem what so ever. When ever you can take an engine that spins a bearing there and replace it without any machine work to the crank at all and have it run for 4 years without a problem and do it 2 5 or 6 engines with same results. Then If you think the crank needs turned ,then you have no idea what you can get by with and what you can't. When you are taught old school you know how to get it done without all the extra BS they taught you in school. You got nothing on the old timers sport. Have a good day.


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RE: 1995 Astro van 4.3 vortech over heat help needed

Sport? Never used remanufactured parts? Old Timers? Insults from someone that was stumped by a clogged used radiator? Bragging about poor workmanship habits, and trying to use them as anecdotal evidence of superior skill and insight?

Sorry, your just not worth any more of my time and you are wrong on almost every point you attempted to make.


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RE: 1995 Astro van 4.3 vortech over heat help needed

Linda....don't waste time getting into a battle of wits with an unarmed man....


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