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Overheating and im out of ideas

I dont think im allowed to post pics yet for whatever reason
But i bought a cheap autozone mechanical temp gauge to verify the stocker. I put the auto zone gauge sender in the same spot as the factory one was. In the head between the fist 2 cylinders on the drivers side. Both give me the same results + / - 10 degrees, but still hot
 
Ok did you check the impeller distance on the water pump? I just found my bbc one was WAY off.
 
Hello from another desert rat here in AZ...

I had the same issue with an old CJ 304 V8 of mine.....new water pump, several thermostats, new 3 core radiator, hoses, shroud, coolant reservoir yadda yadda yadda....still overheated.

What it came down to was the exhaust piping. The 304 I had was bored .040 over and I was running a single stock pipe at I believe 2 1/4 inches...can't remember exactly. Anyway we increased the diameter of the exhaust pipe greatly to like 2 3/4 or 3 inch and even kept the single pipe running through a cat and the problem was solved....just a thought.

With a K5 and a new 350, you may consider widening the pipe or converting to dual exhaust and she'll probably run cooler, IMO.
 
I have not.... although im not exactly sure how or where to look for that. Probably just buy the new $40 water punp
 
It cant be the fan. The reverse rotate water pump fan will not fit on the standard rotation fan clutch. I know that one from experience.

Verify the tstat is in right, make sure you use one with a bypass hole and check your timing. Excessive timing can generate ALOT of heat.
 
Stomis said:
It cant be the fan. The reverse rotate water pump fan will not fit on the standard rotation fan clutch. I know that one from experience.

Verify the tstat is in right, make sure you use one with a bypass hole and check your timing. Excessive timing can generate ALOT of heat.
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But a reverse rotation fan & clutch assembly will bolt onto a standard rotation water pump. The whole clutch and fan assy could be the wrong one.

Been through this one with a friend that had a similar issue, I happened to notice the blades spinning in the wrong direction. Replaced it with correct one, fixed the overheating problem.
 
The spring on a t-stat goes into the intake, the pointy thing points up... Even without a shroud it still shouldnt get that hot, that fast. And really, I can run my BBC without the elec fans on, no mechanical fan, and it will hit 225ish and stop, then I switch the fans on and it stays at 185 no matter how hot it is, just sitting and runnin in the driveway. I would guess waterpump, the waterpump/fan combo, or possibly do they need a bypass at the intake from waterpump to pass water through the intake until the stat opens, like a BBC needs?
 
How much time has it actually been run? And did you put a new waterpump on when you installed it? the warranty is no good without reciepts for a new radiator and waterpump . I have the exact same motor in my kids 72 blazer. It ran pretty warm for quite a while during break in. Not sure if it was THAT warm but I remember 200+
 
One other thing to keep in mind... the thermostat is designed to start opening at the rated temp. That does not mean it will be fully open at the rated temp. Example:

Type.......... ............ Pellet
Rating ......... 180 degrees
Begins to Open at...... 177º-183º F
Fully opened at......... 212º F

So while 260 is way too high, 200 to 220 is fine while under load and so forth.

One other thing - you put in new coolant ... did you mix it 50-50 with distilled water? Running straight coolant is a mistake, it should be mixed (unless you bought pre-mixed).

I'll second the radiator cap check. And the overflow tank check. Is that all working? And did you pressure test the coolant system? It's a simple tool you put on the radiator cap fitting and pump it up.
 
4xcrazy said:
But a reverse rotation fan & clutch assembly will bolt onto a standard rotation water pump. The whole clutch and fan assy could be the wrong one.

Been through this one with a friend that had a similar issue, I happened to notice the blades spinning in the wrong direction. Replaced it with correct one, fixed the overheating problem.
Click to expand...

Yeah but the reverse rotate pump has a different size shaft to center the pulley and fan making the standard rotation stuff either not fit or not center at all on the pump, I dont remember which.
 
zonacats said:
Here's what I got, and 84 K5 with a brand new crate 350 from GM put in a week ago.

-New 350 (260hp / Gen 1 engine)
-New Edelbrock intake / 600 CFM carb / air cleaner
-Mostly all new engine parts (hoses, distributor, plugs, wires, etc)

A few days after getting the engine put in I noticed that the temp was staying normal for a few minutes and then rising pretty high (maybe 240 - 250 ish) for about a minute then going back down to normal (180-190 ish) and staying there for a few minutes then going back up again, then down, etc..

I figured maybe the thermostat (180) was sticking (even though it was also brand new with the engine). So I replaced it with another one and had the same problem. I then bled the system of any possible air pockets (twice) and same thing.

So I thought something is either clogged or to old in the cooling system so I went on a replacement spree and put in:

-brand new radiator (HD)
-all new hoses and clamps
-new fan clutch (HD)
-new temp sender unit in the head (and cleaned the connection up in the wire)
-all new coolant (obviously)
-made sure all the air was out of the system

So I get all that stuff put in and figured, ok, basically everything that runs coolant is brand new. Well, I start it up and the temp eventually rises even higher now (almost 260) and pretty much stays there so I had to shut it down. A few more test after it cooled and same problem.

So now Im at the point were its got to be the gauge. So I run to napa and grab a mechanical temp gauge with sender and installed it. I just put the new sender in and ran the cable out of the hood and through the window (redneck I know, but I just wanted to monitor it instead of actually instill it). At first it seemed better. The initial start up and warm up in the driveway stayed around 200ish. Then I went on a cruze around the block and it went up to 220-230. It came down a few times to about 190 but then went right back up.

Im at a loss right now on where to go from here. Any suggestions?
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Does the temp continue to go up and down if you keep driving? That fluctuation indicates thermostat to me. At thispoint, I would remove the thermostat and drive it and see what it does. And you don't have to buy any high priced parts to do it.
 
Well, the temp did go up and down at first, but over the weekend it progressively got worse, to the point that last night it just heated up and stayed there.

I called the mechanic that installed the engine and told him everything. I figured that since he installed it and also charged me for a new water pump that he should fix it. I had it towed to his shop this morning so we'll see what happens. I made of list of all the suggesting from this thread and told him those ideas.
 
zonacats said:
Well, the temp did go up and down at first, but over the weekend it progressively got worse, to the point that last night it just heated up and stayed there.

I called the mechanic that installed the engine and told him everything. I figured that since he installed it and also charged me for a new water pump that he should fix it. I had it towed to his shop this morning so we'll see what happens. I made of list of all the suggesting from this thread and told him those ideas.
Click to expand...

That's the best advice you could give yourself.
 
bot0611 said:
what about the coolant passeges, i remeber something when i replaced my intake manifold that theres was a passage that needed to be blocked on the RH side Passenger side.
Click to expand...

That was probably the exhaust passage for EGR. Rear right/passenger side.

Interested to see what the mechanic finds.
 
Just got the blazer back. Turns out it was the wrong water pump (reverse rotation). Thanks everybody for your help!
 
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