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overheating 400sb part 3 - isolating the problem
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TonyD
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Joined: 26 May 2006
Posts: 26

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PostPosted: Thu Jun 29, 2006 3:14 pm    Post subject: overheating 400sb part 3 - isolating the problem Reply with quote

hi guys,
installed new water pump, ran it w/o the stat. the coolant is flowing now and circulting throughout the engine, getting all the hoses hot - but it still overheats! i guess an air pocket wasnt allowing the stat to open.?

does this mean it is in fact an air pocket? or a cracked head? or? what should be next step? ive reached the end of my ability and am very close to dropping it off somewhere to pay big bucks to get fixed. Sad

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10sec.et
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Joined: 29 Mar 2006
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Location: Houston,Texas
346658.74 points


1969 Oldsmobile Cutlass

PostPosted: Thu Jun 29, 2006 5:22 pm    Post subject: Reply with quote

do you have a temp gun to verify that the engine actually is overheating? you said before that the tubing to the gauge was on the header. possibly a calibration problem with the gauge.

you will also have a overheating problem if you dont use a stat or a restrictor. the water circulates too fast and cant dissipate the heat.

i dont remember, did you say before that it overheats idling? if so make sure the fan is working properly and there is a fan shroud on the radiator. if its pulling enough air across you should be able to drop a shop rag down in front of the radiator and the airflow will hold it there. make sure there are no areas on the radiator that are significantly cooler than the rest. this will indicate clogged tubes.

if you still suspect a cracked head you can buy a "block tester" from the local parts store. follow the directions. its pretty easy and a lot cheaper than shop diagnostics.

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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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TonyD
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PostPosted: Thu Jun 29, 2006 5:31 pm    Post subject: Reply with quote

the previous aftermarket gauge was routed near the header. i removed it, and hooked up the factory guage - same reading.

didnt know it would overheat without a stat? they're cheap, ill buy a new one, and drill a small hole it and see if it opens to allow flow.

yes, overheats idling. ill do the shop towel test as well. but i did watch inside the radiator while it was running.. seems the flow quite well.

ill pick up a block tester when i get the new stat. the place down the street said they could diagnose for $40 which i thought was reasonable.

thanks for the help 10sec.

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beersngars
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Joined: 04 Feb 2006
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1948 Chevrolet Coupe

PostPosted: Thu Jun 29, 2006 5:32 pm    Post subject: Reply with quote

As 10sec said, verify the thing is overheating. Ditto on the stat. Is it overheat when moving, idling or both. What is the actual water temp? Are you sure the water pump is turning the right way? Did the problem just start and if so, what changes did you make.
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TonyD
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PostPosted: Thu Jun 29, 2006 7:28 pm    Post subject: Reply with quote

got the car with this problem. the water pump is for a v-belt 68-76 so its right. overheats when moving and idling.

i just dont understand why the stat wouldnt open? then i run it w/o and it still overheats. but i guess it does that with no stat. maybe i replaced the old stat with a bad one?

the temp goes up to 230 can keeps climbing, i shut it off then.

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10sec.et
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1969 Oldsmobile Cutlass

PostPosted: Thu Jun 29, 2006 8:40 pm    Post subject: Reply with quote

Quote:
just dont understand why the stat wouldnt open?

the t-stat wont open if it is surrounded by an air pocket. thats what the 1/8 hole is for.

if installing the stat doesnt help try running water across the radiator (with a garden hose)when its hot,while its running, and see if the temp comes down.

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af2 wrote:
It seems we can look at our magical Balls and come up with a fix?

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bill jones
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PostPosted: Thu Jun 29, 2006 9:10 pm    Post subject: Reply with quote

-A few things that I think you need to do is to move the temp gauge sender to the front crossover of the manifold rather than down on the side of the head anywhere near the header.
-------------------------------------
-I take all my mechanical gauges and stick them in a small pot of hot water on the kitchen stove----and watch the gauge needle in relation to right when the water starts to break into a nice rolling boil---should see about 212 on the gauge when the water is just starting to actively boil if you are at sea level---and I know that at 4200 elevation the water boils at about 202.
-------------------------------------
-I would also drain the radiator temporarily---with the lower hose removed -----plug the lower outlet someway so that you can pop it wide open real quick---like hold your hand over the outlet----fill the radiator clear full of cold water-----then count the seconds it takes to drain the radiator when you pull the plug.
-the water should gush out of there in about 15 seconds.
--------------------------------------
-Retarded timing really makes an engine heat up.
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af2
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Joined: 01 Sep 2003
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Location: grassvalley, ca
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1933 Willys Coupe

PostPosted: Thu Jun 29, 2006 9:13 pm    Post subject: Reply with quote

TonyD wrote:
got the car with this problem. the water pump is for a v-belt 68-76 so its right. overheats when moving and idling.

i just dont understand why the stat wouldnt open? then i run it w/o and it still overheats. but i guess it does that with no stat. maybe i replaced the old stat with a bad one?

the temp goes up to 230 can keeps climbing, i shut it off then.


Just by chance is the water pump in reverse rotation? You never know. You inherited a problem and have to make it right.
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TonyD
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PostPosted: Thu Jun 29, 2006 9:22 pm    Post subject: Reply with quote

10sec.et wrote:
Quote:
just dont understand why the stat wouldnt open?

the t-stat wont open if it is surrounded by an air pocket. thats what the 1/8 hole is for.


you're right. im going to try and drill my current stat. will also boil it to make sure it opens.

going to check the timing too.

thanks for all the advice so far everyone.

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TonyD
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PostPosted: Sat Jul 01, 2006 5:20 pm    Post subject: Reply with quote

PROBLEM SOLVED!

replaced the stat with a new one with a drilled hole - got it to flow correctly. AND i was getting an inaccurate reading fomr the sender in the head.

the guage works fine, its just the reading was 250+! when it was never getting over 200. checked it with an infared temp guage. im going to hook up the guage to the intake for a more accurate reading.

THANKS TO EVERYONE HERE FOR THEIR HELP. .. NOW ITS TIME FOR THE BURNOUT VIDS!!!!

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artinla
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Joined: 09 May 2006
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1971 Chevrolet Nova

PostPosted: Sat Jul 01, 2006 6:03 pm    Post subject: Reply with quote

Man, I do like burnout vids.

For a laugh, google "2 quick novas burnout" and go to that page. There are some real $hitboxes on there but the guys are hilarious. I have a background pic that I got from there of some guy single-tracking on his mom's sidewalk. It is a green nova, you will see it.

While you are at it, watch this vid. I am no Ford man, but you gotta love those new 'stangs.

http://www.youtube.com/watch?v=g1g5p3YQzMM

Glad you got the car fixed.
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af2
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1933 Willys Coupe

PostPosted: Mon Jul 17, 2006 7:41 pm    Post subject: Reply with quote

THAT CAR HAULS!!!!!!!!!!!!!

There is another one outside that is impressive also!!!!
To keep on topic: Glad you fixed it!
If Smoke could have vid clips that would be great!!!
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SMOKEmUP
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Joined: 30 May 2002
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1979 Chevrolet Camaro

PostPosted: Mon Jul 17, 2006 8:48 pm    Post subject: Reply with quote

af2 wrote:
If Smoke could have vid clips that would be great!!!

Videos really chew up the bandwidth. I don't think it's worth it IMO.
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af2
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1933 Willys Coupe

PostPosted: Mon Jul 17, 2006 8:52 pm    Post subject: Reply with quote

smokemup wrote:
af2 wrote:
If Smoke could have vid clips that would be great!!!

Videos really chew up the bandwidth. I don't think it's worth it IMO.


I see what you meen!! Links work just fine. Did you watch that link by the way?
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Paul P
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Location: Townsend, Mass.
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1971 Chevrolet Chevelle

PostPosted: Tue Jul 18, 2006 3:32 pm    Post subject: Reply with quote

I like that video that is what N2O is all about.
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