engine still overheating

[ocbaud]

okay, i thought i fixed all of this crap

i replaced the water pump gaskets and checked the pump last week, along with putting in a new 180degree high flow tstat, changing the temp sensor for the gauge, and changing the temp sensor for the fans(200-on/180-off) it still over heats, even with the fans running. usually it stays right around 210 or so and sometimes the guages will peg out to 260 and slowly come back down.

i dont know what to do
whats the easiest and cheapest way to check for a blown headgasket? the reason i ask is because its over heating, and the truck doesnt seem to have as much power as it should, the plugs look alright though.
maybe its just the radiator needs flushed, but it was fine before i swapped rear gears....

its its a head gasket, i swear, i'm gonna fix it and sell my truck. i cant afford it as it is

[boxrodz]

I'm not sure all that you checked or replaced, but it sound as though you gone through it all. I threw a quick list together of what could cause overheating in case you overlooked something:

1. The incorrect coolant level and mixture.
2. A non-working pressurized radiator cap (15 lbs.).
3. Fan belt(s) not properly tensioned.
4. Water pump venthole plugged.
5. Plugged radiator causing uneven temperature rise from right to left with possible cold spots.
6. Non-working or incorrectly installed thermostat.
7. Intake manifold cross over (at the front) plugged.
8. Passages in the heads plugged.

To check for a leak at the head gasket:

Drain just enough of the coolant until the level of coolant is just above the heads. Disconnect the upper hose and remove the tstat and fan belts. Start the engine and rev the engine quickly a few times while watching the coolant. If you see a significant rise in the coolant level or bubbles then exhaust gases are leaking into the cooling system.

Good luck. Hope it's something simple causing your problems.

[ocbaud]

Originally Posted by boxrodz

1. The incorrect coolant level and mixture.
- all good
2. A non-working pressurized radiator cap (15 lbs.).
- 16lb new cap
3. Fan belt(s) not properly tensioned.
- properly tightened belt, i have electric fans
4. Water pump venthole plugged.
-how would i check that?
5. Plugged radiator causing uneven temperature rise from right to left with possible cold spots.
-could be, i've never had the rad. flushed, but it didnt overheat until i put in my new gears
6. Non-working or incorrectly installed thermostat.
- good tstat
7. Intake manifold cross over (at the front) plugged.
-shouldnt be, 1 year and about 8000 miles on engine
8. Passages in the heads plugged.
- same, 1 year old

the machine shop installed the heads. he assembled the complete long block. and like i said, it never overheated until i put in new gears.

and i was thinking more of a compression of leak down test to see if i blew a head gasket

[boxrodz]

To check your water pump, warm up your engine. While running the engine squeeze the upper radiator hose. You should feel a pressure surge. As far as the vent hole goes, you should be able to carefully probe the hole to make sure that's not plugged. Probably a unlikely cause.

Yeah, I think you could perform a leak-down test. It may not necessarily tell you if exhaust gases are getting into your cooling system.

After extended idling (in Park), does the engine overheat? If so, do you hear any cooling system noises like surging/gurgling, heater hose vibrating/moving, radiator hoses collapsing/expanding?

Are you running a shroud with your electric fans?

[ocbaud]

the water pump should be fine. there was pressure and all the hoses are not collapsing. i have never seen a vent hole on it.
yes, the truck will overheat if it idles for a long time in park or while just driving around.
i also made sure to get out all air trapped in the system, so that couldnt be it. i dont hear anything in particular that sounds like a cooling system problem.

my elec. fans have shrouds built around them.

[boxrodz]

How large is your radiator?

[ocbaud]

Originally Posted by boxrodz

How large is your radiator?

stock

[Slonaker]

Originally Posted by ocbaud

stock

My '86 came with a 2 row stock. A 3 row was a drop in replacement. The external size of the tanks and everything is identical. Oh, and the three row is cheaper.

Slonaker

[pedrofixlater]

changing your gears has increased your engine rpm's sounds like your radiator cant handle the that. install a three core radiator Advance Auto Parts has 3 core rads for 98.00

[boxrodz]

I would think that a 3 row should handle your engine setup. Not too sure about a 2 row. As Slonaker said, a three row drops right in.

Pedrofixlater - I figured that if his engine overheats while just sitting and idling then that would eliminate the gear change.

If it's not the radiator, then I'm wondering if a timing or fuel mixture issue could be causing your overheating problems (and loss of power).

[swervin ervin]

If your radiator is in good shape, I say it's your water pump. I know you said it has pressure and all but I firmly believe it to be a pump problem. Why not go buy a cheap pump and try it? Water pumps will cause strange things sometimes.

Believe me, unless something changed with the radiator or pump, there is no way a gear change would cause it to overheat.

[Boog]

That gear change can make a difference in how well the cooling system works but only while driving. That truck should have a 3 row rad for sure. A gear change will not affect the temp at an idle though. If it's actually getting hot at idle you could have a blockage in the system ( rad ). If it is only the gauge showing it to be hot then you have another problem altogether.
A well equipped garage should have cooling system testing equipment, pressure test it and see if combustion is getting into the cooling system.

[BADGMC]

Every truck and engine acts differently. I still have a replacement 2 row radiator and with my combo it only gets up to 200 when going uphill for a long way while going slow. Never has a problem idling or driving around. Check for bubbles coming out of the radiator cap for a blown head gasket. My friends Nova had an overheating problem and a good radiator flush job fixed it right up.

[ocbaud]

alright, when we talk about how many cores the radiator is, i'm not sure what its referring to.

my radiator, if you take the cap off and look into it, has 3 rows of tubes beside each other going all the way down.

[BADGMC]

Yep 3 rows of tubes is a 3 core.

[gchemist]

Time for http://www.stewartcomponents.com/
Get an aluminum 4 core radiator.
Buy a modine thermostat. All other suck by comparison. I've gone through several brands.

[Boog]

Eric, I have forgotten what all you have done to it so far.
Did you put in a mechanical temp gauge to verify what the stock gauge is reading? Is the radiator actually boiling over into the coolant recovery tank? If it is in fact getting to 250, 260 it should be steaming under the hood. You need to know if it is really getting as hot as the factory gauge says it is or mearly giving false readings. I had the same gauge readings happen on my 85 Blazer. It would slowly go almost all the way to the hot side within minutes after starting and let idle, then just as slowly go back to normal but it was only a false reading as the engine itself was not overheating. Regretably I did not find the cause of my prob before I sold the truck. I did install a 165* stat, sending unit and new factory gauge. Only after putting the 165* stat back in did the gauge read normal again. I bought numerous stats trying to find the prob also. Winter is over. Put the 165 stat in and see how it reacts. What have you to lose?

[swervin ervin]

Originally Posted by Boog

Only after putting the 165* stat back in did the gauge read normal again.

How did putting in a 165 degree thermostat make the gauge read right again??

I still say swap out the pump for a cheap Autozone one to see what happens. Eric has changed thermostats already to no avail.

I've got 3.73 gears and a stock 3 row radiator and have never had one bit of overheating. I have a Stewart Components water pump and swear by them. Water pumps have more to do with cooling than any other single thing on the truck.

Mike

[Boog]

{How did putting in a 165 degree thermostat make the gauge read right again??}
The gauge reading remained steady again, normal.
With the 195* stats in the gauge would head right over to peg at hot side after cold startup and after a few minutes it would come back down and register high while driving also. My engine was never overheating. It was only a false reading through the gauge.
I put in new radiator, water pump and numerous stats believing it was cooling a system problem. Mine was not.

[badone07]

I didn't remember what else you did so I had to look at your website again. Nice setup there, except think I would've used full length headers and bigger carb. Were the heads re-torqued? What intake you running, Holley 300-36 street dominator? Assuming your timing and carb adjustments are correct. Looks like your pulling the electric temp from the head. Guess you plugged the extra bung up by the water neck. Get a cheap mechanical water temp guage setup. Screw the sender into the intake manifold, right there. Then see what the temperture is. There is no way I would've dumped all that money into that motor and relied on factory electrical guages. Personally, also not crazy with the electric fan setup you have there. Would've tried a setup that covered more radiator surface area. If the temp still doesn't come down, I would try the stock shroud and a clutch fan, since you've done just about everything else. I doubt it's the gears. Currently running 4.10's and only previously had temp problems with 2 cracked heads.

[ocbaud]

i think i've figured out its an electircal problem for sure now.

by the tstat housing i have a sender for my electric fans. its supposed to turn the fans on at 180 degrees and off at 165 or so.
well the fans turned on when the gauge was around 210ish and then turned back off when the gauge was around 240ish......

i have a new temp sender for the guage located in the drivers side head. so its either the wireing going from the sender to the guage, or the guage itself.

[lolife99]

ocbaud,... I would try the "original fan" with a heavy duty "clutch" and the stock fan shroud. I had a cooling problem years ago,... and this was my fix.

[swervin ervin]

Eric,

did you just say on at 210 and off at 240???? Ain't this backwards???

My switch is in the drivers side head for my fans and the temp sender is in the intake. Coolant temp readings are more true coming from the head as this is the hottest spot on the engine. So, I figured I would be better off with the fan switch located there. My gauge reads lower with the sender in the intake though as this is probably the coolest spot on the engine, right at the thermostat housing. This is the reason you always see the temp sender in the head stock. You have to take this into consideration and remember your normal coolant temps are probably higher than your gauge is showing the way I have it.

Anyway my point is, my fans cut on at 210 and off at 180. But, and this is a very big but, they never come on. I have to sit still for several minutes after it gets to operating temp, even in the hottest summer days. With a switch cutting them off at 165 is way overkill. It's not good at all for a performance engine to run this cool. You need a 180 degree stat and the fans cutting off at 180 IMO. Also, I don't remember what fans you bought. If it's some Autozone cheapies, this is a strong concern to me. Reliability is a major factor. Another major factor is how many amps they use. If you didn't have to go with a higher amp alternator in order to run them, they are not drawing enough power and will not pull enough air to cool it down when needed.

Mike

[ocbaud]

Originally Posted by swervin ervin

Eric,

did you just say on at 210 and off at 240???? Ain't this backwards???

My switch is in the drivers side head for my fans and the temp sender is in the intake. Coolant temp readings are more true coming from the head as this is the hottest spot on the engine. So, I figured I would be better off with the fan switch located there. My gauge reads lower with the sender in the intake though as this is probably the coolest spot on the engine, right at the thermostat housing. This is the reason you always see the temp sender in the head stock. You have to take this into consideration and remember your normal coolant temps are probably higher than your gauge is showing the way I have it.

Anyway my point is, my fans cut on at 210 and off at 180. But, and this is a very big but, they never come on. I have to sit still for several minutes after it gets to operating temp, even in the hottest summer days. With a switch cutting them off at 165 is way overkill. It's not good at all for a performance engine to run this cool. You need a 180 degree stat and the fans cutting off at 180 IMO. Also, I don't remember what fans you bought. If it's some Autozone cheapies, this is a strong concern to me. Reliability is a major factor. Another major factor is how many amps they use. If you didn't have to go with a higher amp alternator in order to run them, they are not drawing enough power and will not pull enough air to cool it down when needed.

Mike

exactly what i mean. the sender for the fans are supposed to turn them on at 180 off at 165, but the guage isnt reading currectly, because the fans would turn on, and then shut off after the guage has gone UP.
i'm gonna change the sender back to the 200/on-180/off i had in there

[Prerunner1982]

Eric, try a mech guage in the head to see what it really reads. It very well could be the wiring and/or guage. You could mount the mech temp guage on the panel between the windshield and hood.