overheating

[53burb]

My engine is getting hot. I know the sender is correct because the engine overheats and the water boils. The problem started a few weeks ago. I thought it was the thermostat. I have replaced that. I have replaced the engine. I have replaced the radiator with a 4-core unit (not new). I replaced the fan clutch. The fan only sticks out of the shroud about 1/2 to 1 inch. The upper hose gets pressurized. The only thing I can think of is the water pump. It was replaced about a month ago. I started having the problem after that. I replaced it because the original one was leaking from the weap hole. I checked the p/n they gave me, it was the right one. Do they happen to make a reverse rotation short-style water pump?? I know somebody mentioned this before. The only thing I can think of it got put into the box I needed by accident. Anybody got any other ideas???

[z7199]

I dont know where you got the pump but I know that I have had problems with the pumps from Auto Zone. I went through a few on a Grnd Marquis I used to have. Same with Alternators. I would take it back and tell them it does not seem to be working properly

[53burb]

I got it from Checkers/Kragen. I think they sell the same parts.

[shifty]

This is probably a dumb question, but is it possible for your engine to run hot if your heater core is plugged up? Also, one more dumb question, what engines actually have reverse-flow water pumps?

I'm not looking at an engine right now, so I can't remember how all the water lines are running and I honestly don't know about reverse-flow pumps, I just know they exist.

[53burb]

The heater core is bypassed and engines with serpentine belt systems use reverse rotation waterpumps.

[chickenwing]

You could pull the radiator cap off. Bring it up to temp and wait for thermostat to open and check for coolant flow. Upper hose could be pressurized because the coolant is hot, don't think that would neccesarily mean flow is gauranteed. You mentioned your radiator is used. (Not trying to insult you just bouncing things around) The radiator doesn't have a bunch of repairs to it? No passages pinched off and soldered? Coolant pretty? Been playing with the timing? Other n that, you got me stumped.

Edit: Never heard of a reverse rotation short water pump. But ya never know...

[Brainchild]

I'd pull the thermostat and put it in a pot of boiling water with a thermometer,and see what temp it opens at.
Do the easy things first

[blazerparts]

I'm with him ^, check the thermostat

[71C/10]

if you have a serpentine set up the water pump may not be the right one. it would be very easy to buy the wrong one. the easiest way to check for this condition would be to start the eng when cold & let it warm up. see if the upper hose gets hot first or the lower hose. if the upper hose gets hot first the water pump is correct. if not you will need to get the other style pump.

[GloryHound]

Water pump might be incorrect or if it's remanufactured could be the 1 in a 100 or so that does not work. Also some water pumps come with little plastic caps that actually get inserted into the pump inlets and outlets, if you left one of those in it can cause all kinds of problems. One thing that gets overlooked alot is the radiator cap. If you have the wrong one on the radiator it can start to cause water vaper lock problems. Also some thermostats can be bad from the factory, the pot of boiling water is a good test for this.

[53burb]

I replaced the waterpump today. It seemed to do the trick ok. I drove to a gas station about 5 miles away. The needle was about 1/4-1/3 of the way, everything was ok. After a few minutes, I started it back up and the needle was in the middle. I drove it home and parked it. I am only running straight water right now. Tomorrow, I am going to drain the radiator and put in a couple of gallons of antifreeze and go from there. Does anybody think that will make a difference. I haven't timed it or adjusted the carb correctly yet.

[CHEVIBUBBA]

Glad it's fixxed.now, don't mess it up by putting antifreeze in it!
antifreeze should only be used when the temps are likely to drop below freezing.
if your climate is gong to be at or near freezing in the next month or so, only put in enough antifreeze to counter the "freeze".
it has 1/3rd the ability to transfer heat.
prestone has a great bottle of waterpump lube with corrosion inhibitors in it that will allow you to use straight water.
use it & a 20-22 psi new cap & you'll have boilover protection to about 260!& your cooling system will remove at least twice as much heat as it would with antifreeze blended in.
btw, you just cut the life of that water pump in half by running it on straight water.
water has no lubricating properties.

[53burb]

It is not fixed now. It was running and cooling fine until I stopped at the gas station. After I started it back up, the needle went to about the midpoint and it was running like #@%$. That is why I was going to try the antifreeze to help keep it cool. Do they sell that stuff from Prestrone at Checkers or AutoZone??

[CHEVIBUBBA]

perhaps some more details about your engine combo will help diagnose this problem.
even wally world carries the prestone waterpump lube.i use it as instructed on the bottle.
it's common to see the temp come up after sitting 5-10 minutes due to heat soak.if it was at 180-190 when you stopped it could easily get above 212 & cause boiling if the system isn't holding pressure.
why the temp increase caused it to run like crap may be due to carb calibrationleaking head gasket.dunno.not enough info.
you can check the t-stat as previously stated.
how is the lower hose?
i assume you inspected it when you changed the pump.was the anticollapse spring intact?
to check for flow initialy, remove the t-stat housing & t-stat while the engine is cool.
with water up to the t-stat opening, turn the engine over.water should shoot out .this verifies water flow.
you can reinstall the t-stat housing w/o the t-stat, start it & look in the radiator.you should see water turbulence.if not, there is a restriction between the t-stat housing & the opening.
did you have the radiator inspected?see any steam rising from it or wet stains or wet spots?check both sides.
when it is at norm operating temp check the front of the rad with your hand.you should feel airflow from the fan & the temp will feel about the same accross the core with any temp difference being lower to the pax side.
if no airflow or little the fan is gimp.i recomend a large electric fan but 2nd best is a thermostatic clutchfan if it works.
another symptom of a malfunctioning fan is above 35-40 temp is good.in traffic or below 35 temp rises greatly or it overheats.
if temp across the core is sporadic or low the rad is probably blocked.have it rotted out & checked.also check the cap mount for damage or cracks

next on the list is the rad cap.is it over a year old?
replace it. get one with 20-22 psi if possible.they are their you'll just have to hunt for them.lever caps are pretty much useless.unless it's marked 20-22 psi.

if you suspect the cap is good have it tested & the whole system at a rad shop.most do it for free.good for business.

[CHEVIBUBBA]

can you be more specific about how it was running like "#@%$" ?was it backfiring, blowing black smoke,etc?do you have an open air cleaner?could've been sucking in steam.after you left the station did you get up some speed?go for a bit?did the temp drop?
"I know the sender is correct because the engine overheats and the water boils"
the sender could be wrong.water boils at 212 unless under pressure.this would be about 1/3-1/2 on the guage iirc.
you could get a new sender & check it.
i think you have a couple things going on causing this.system not holding pressure, fan not working correctly.
just thinkin'

[53burb]

ChevyBubba,
Thanks for all the input. The original radiator was a 3-core and I had the same problem before I pulled the engine. The radiator in there now is a 4-core. It appeared to be ok before I installed it. Previously, the sender was installed on the waterpump. It is now on the drivers' side head. As for the way it was running after I started it up at the gas station, it seemed to be running rich, and it stalled a couple of times before I got it going. Would this be because the carb needs adjusting?? I know the mixture screws only affect the idle circuit. Does it make sense to say that since I have a new cam, the fuel pump is affected by this and is now giving the carb too much fuel. I am using an Edelbrock 1406 w/o a regulator, but I didn't have problems with the old engine.

[53burb]

I forgot to say it is an open element breather. The temp didn't drop on the way home. Do you think sucking in hot air would make it act like this??

[CHEVIBUBBA]

there are too many variables involved to conclude the carb needs adjusting.
great carb btw.
i assume you don't have alot of miles on this new engine.did you build it?
has it always done this?
did you break the cam in correctly?
install correctly?if the cam was not degreed on install it could be timed incorrectly enough to cause overheating.not likely if this hasn't always happened.
i've been assuming the engine was doing fine & then suddenly it started overheating.
is the timing set correctly?too much advance or retard can cause overheating but, you would have noticed either pre-ign. pinging on accel. or sluggish performance.
i don't see how the fuel pump could be feeding too much fuel causing this.
too much fuel cools the engine.
a lean mixture can make the engine run worse if it gets hot/overheats.
how fast were you going on the way home?over 35?
should've dropped the temp.unless the t-stat was stuck open.
how long does it take to warm up?
i'm just throwin ideas at you.
check what you can as listed.post your findings as well as details on the engine install & if it always did this.
let me sleep on it i'll give you an answer in the morning,(there's a song there somewhere)

[CHEVIBUBBA]

oh,sucking in hot air? probably not. especially when engine performance didn't improve as speed increased.
if it ran like poo poo at first but then cleared up it could've been a leak in the system allowing the engine to suck in steam.
do you have a coolant recovery tank?
you need one.
i'll talk at ya tomorow.

[CHEVIBUBBA]

i hate not being there to diagnose the problem!

[53burb]

I will answer all your questions a little later. I am at work right now. I appreciate all your help. There will be more for you when you get up...

[zeeklu]

If you have a reverse rotation water pump would you need a reverse rotation fan also? Chris

[53burb]

It is a standard rotation waterpump and fan. I do have a coolant recovery tank with a new 13lb closed system cap. I didn't build the engine. I bought it from a shop. It has a Comp Cam HE268 installed straight up. I haven't timed it yet. The engine does seem sluggish. I expected more from this engine. I was going probably about 40-50mph on the way home.

[53burb]

Today:
-Drained the radiator and refilled with 2 gallons of antifreeze - no change
-Removed the thermostat - no change (I removed the thermostat when it
was still hot and it was opened).
I retarded the timing slightly (I think) - No change
The only thing left I can think of is the radiator. That means the original one and the used 4-core one are both bad. Would the spark plugs have anything to do with this?? I reused my old ones. They looked ok. They are Bosch Platinums. The old engine blew a head gasket, but the plugs looked ok. How about thr radiator cap?? It is a 13lb closed system cap.

[68w/sbc406]

not a truck, but, my honda would over heat cause the timing was off. i couldnt get the timing right by adjusting the dizzy. ended up being the belt was one tooth off. id get a light and set the timing if it has never been set