Engine runs hot

[newbraunie]

I have read several posts and picked up many tips and ideas. I have thoroughly been through the cooling system but engine still runs hot. I have a 292 6cyl with around 15,000 miles on rebuild. Manual transmission.

new water pump
3 row radiator - just rodded out
have tried 195, 180 & 160 thermostats - back to 180
new temp sending unit
hooked up alternate gauge - reads same as factory
ditched 4 blade stock fan - installed 6 blade
checked dash gauges ground wire
new 13 lb radiator cap
recent tune up - timing at 4 btdc

The engine does not act like it is running hot. No knock, rough idle or coolant boil over. The fan blade change out was the last thing I did and it seemed to help a bit. Factory gauge runs a little over 2/3 instead of 3/4+ (see pics of gauges taken before fan replacement). The only cooling system issue I can think of at this point would be the new sending unit is faulty. The sending unit I replaced gave same reading though so what is the chance of 2 faulty sending units. There is a slight amount of valve chatter, could valve lash cause engine to run hot? I have not tried drilling holes in thermostat, maybe an air pocket? Maybe the engine is not running hot but looking at that gauge running past the 1/2 way mark drives me nuts!!!

http://i420.photobucket.com/albums/p...16/Misc002.jpg
http://i420.photobucket.com/albums/p...16/Misc003.jpg

[mr48chev]

Ok why do you say it is running hot? is it the reading on the gage or is it boiling over? A little explanation might help here.

If I didn't trust the stock electric gage I'd buy a good mechanical temp gage and mount it under the dash and see exactly what the real temperature was.

[cdowns]

i agree on double checkin gauge readings// i have a known good thermometer that i just dip into the radiator//you can get pretty acurate thermometers at the supermarket or cooking supply store//to check a thermometer for accuracy just dip in boiling water

[RustenPaines]

Test the thermastats. Get a good one form say Stant. Drill a few little holes in the flange of the thermastat to allow water to flow by the wax filled cup on the thermastat. If you still have a problem remove the thermastat. If that does not work, either your radiator is clogged or the pump is bad. Sorry but its never an easy solution trying to locate a problem like that. Good Luck.

[newbraunie]

Originally Posted by mr48chev

Ok why do you say it is running hot? is it the reading on the gage or is it boiling over? A little explanation might help here.

If I didn't trust the stock electric gage I'd buy a good mechanical temp gage and mount it under the dash and see exactly what the real temperature was.

No boil over but both gauges indicate it is running hot, 240 degrees idling in driveway. I will look into mechaincal gauge, these do not read based on resistance from temp sending unit? I did install temp sending unit with thread sealant on it. Maybe that is causing faulty reading.

[newbraunie]

Originally Posted by cdowns

i agree on double checkin gauge readings// i have a known good thermometer that i just dip into the radiator//you can get pretty acurate thermometers at the supermarket or cooking supply store//to check a thermometer for accuracy just dip in boiling water

Have good meat thermometer, will give this a try. it runs hot even without radiator cap on.

[newbraunie]

Originally Posted by RustenPaines

Test the thermastats. Get a good one form say Stant. Drill a few little holes in the flange of the thermastat to allow water to flow by the wax filled cup on the thermastat. If you still have a problem remove the thermastat. If that does not work, either your radiator is clogged or the pump is bad. Sorry but its never an easy solution trying to locate a problem like that. Good Luck.

It is Stant 180 thermostat, tested prior to install. Radiator is not clogged, just had it rodded out. Gonna try a few other tips before drilling holes in thermostat.

[newbraunie]

Also, I went to back the raditor shop after putting radiator in. He performed test that detects exhaust gases in coolant. None detected. That should rule out head gasket leak. He recommended better fan since there is no shroud.

[GOPAPA]

Just a thought ,,do you have the correct raidiator shroud for this motor and at the right distance? papa

Missed your last post and now am puzzled.. if I read you correctly and you have no shroud,,isn't this your heating problem?

[Luvlegs]

You shouldn't put sealant on the temp sender either.

[newbraunie]

Originally Posted by GOPAPA

Just a thought ,,do you have the correct raidiator shroud for this motor and at the right distance? papa

Missed your last post and now am puzzled.. if I read you correctly and you have no shroud,,isn't this your heating problem?

Inline sixes do not have shrouds, just the small guard that sits above the fan(see pic from board member post). http://67-72chevytrucks.com/vboard/s...ghlight=shroud

I have small block 4X4 shroud but would have to cut it so it will fit. I would hate doing that but have not ruled it out. I am going to look at all other options before doing that. I figure since 6 cyls did not come with shrouds they do not need one?

[newbraunie]

Originally Posted by Luvlegs

You shouldn't put sealant on the temp sender either.

It came out of the box that way so I installed it with thread sealant. I am going to remove sealant and see if that works.

[sneakysnake]

Do you have the fan spacer that puts the fan closer to the radiator?

[kcjones]

With all the things you did, you knocked out about 95% of what normally causes running hot. Have you tried a coolant flush? You can buy a $10 kit from the parts store that adds a threaded hose connector to your heater hose, so you can run garden hose water through it - running or not. I did so on mine a few months back as I was getting no heat from the heater even though thermostat/water pump/heater hoses were good. Got tons of gooey junk out. Heater is hotter now, but still not toasty, so I have have a heater core that's corroded to the point of blocking coolant flow (although that's not your issue, most likely). Maybe there's blockage in the coolant passages...could be gasket sealer, rust, or other junk. No coolant flow = hot block, cool radiator.

[Lobo'74]

Not to steal the thread . . . But where do you get a fan spacer? My 350 is mounted in the inline 6 location so my fan sits just about 1 1/2 or 2 inches away from the shroud.

Back to the thread . . .
Mine ran hot - 240 at idle - but had a small in line 6 radiator and no shroud. Put in a 4 core and a shroud and it runs at 180 - 190 now.

[Prostreet 72]

Originally Posted by newbraunie

I have read several posts and picked up many tips and ideas. I have thoroughly been through the cooling system but engine still runs hot. I have a 292 6cyl with around 15,000 miles on rebuild. Manual transmission.

new water pump
3 row radiator - just rodded out
have tried 195, 180 & 160 thermostats - back to 180
new temp sending unit
hooked up alternate gauge - reads same as factory
ditched 4 blade stock fan - installed 6 blade
checked dash gauges ground wire
new 13 lb radiator cap
recent tune up - timing at 4 btdc

The engine does not act like it is running hot. No knock, rough idle or coolant boil over. The fan blade change out was the last thing I did and it seemed to help a bit. Factory gauge runs a little over 2/3 instead of 3/4+ (see pics of gauges taken before fan replacement). The only cooling system issue I can think of at this point would be the new sending unit is faulty. The sending unit I replaced gave same reading though so what is the chance of 2 faulty sending units. There is a slight amount of valve chatter, could valve lash cause engine to run hot? I have not tried drilling holes in thermostat, maybe an air pocket? Maybe the engine is not running hot but looking at that gauge running past the 1/2 way mark drives me nuts!!!

http://i420.photobucket.com/albums/p...16/Misc002.jpg
http://i420.photobucket.com/albums/p...16/Misc003.jpg

Just food for thought. My 13:1 comp. 468ci runs at 210*F while stuck in traffic. It has an Aeromotive electric water pump, 160* thermostat, dual electric fan, and a four core radiator.

Just a question, do you use a fan shroud?

[newbraunie]

Originally Posted by sneakysnake

Do you have the fan spacer that puts the fan closer to the radiator?

Yes. Fan is 1 1/2 - 2 inches from radiator.

[newbraunie]

Originally Posted by kcjones

With all the things you did, you knocked out about 95% of what normally causes running hot. Have you tried a coolant flush? You can buy a $10 kit from the parts store that adds a threaded hose connector to your heater hose, so you can run garden hose water through it - running or not. I did so on mine a few months back as I was getting no heat from the heater even though thermostat/water pump/heater hoses were good. Got tons of gooey junk out. Heater is hotter now, but still not toasty, so I have have a heater core that's corroded to the point of blocking coolant flow (although that's not your issue, most likely). Maybe there's blockage in the coolant passages...could be gasket sealer, rust, or other junk. No coolant flow = hot block, cool radiator.

I have drained and refilled the cooling system at least 3 times chasing this problem. When I installed water pump I saw that the inside of cooling passages were very clean, saw nothing that would cause blockage. The guy who rodded the radiator said it was not even that clogged but was still in need of rod out. I will check the heater and see if maybe clogged heater core is contributing.

[newbraunie]

Originally Posted by Lobo'74

Not to steal the thread . . . But where do you get a fan spacer? My 350 is mounted in the inline 6 location so my fan sits just about 1 1/2 or 2 inches away from the shroud.

Back to the thread . . .
Mine ran hot - 240 at idle - but had a small in line 6 radiator and no shroud. Put in a 4 core and a shroud and it runs at 180 - 190 now.

I am considering a 4 row even though the radiator guy said I should not need one on a 6 cylinder. Anyone one out ever have any success cutting down a small block shroud to fit an inline 6? My core support has the mounting holes and clips.

[newbraunie]

Originally Posted by Prostreet 72

Just food for thought. My 13:1 comp. 468ci runs at 210*F while stuck in traffic. It has an Aeromotive electric water pump, 160* thermostat, dual electric fan, and a four core radiator.

Just a question, do you use a fan shroud?

Just the stock mini shroud.

[Sport/Truck]

Originally Posted by newbraunie

It came out of the box that way so I installed it with thread sealant. I am going to remove sealant and see if that works.

The only issue it causes is poor grounding of the sending unit. You can check ground with a volt meeter.
Is your block grounded to the frame & firewall?
s/t

[newbraunie]

Will not have time to get my head under the hood until this weekend. Here is what I plan to check.

reinstall temp sender unit with no thread sealant

check water temp in radiator with cap off- although I am concerned with coolant temp at cylinder head.

look into installing mechanical temp gauge to see what temp is at head.

if none of these solve it I will be looking for 4 row radiator and mounting brackets

Thanks everyone for all your input - I will keep you posted

[newbraunie]

Originally Posted by Sport/Truck

The only issue it causes is poor grounding of the sending unit. You can check ground with a volt meeter.
Is your block grounded to the frame & firewall?
s/t

Will check ground to frame and firewall too. Only ground to firewall is stock braided copper strap from head to firewall. Need to check block to frame though. I have voltmeter, how do I check sending unit ground?

[PanelDeland]

One of the Arizona members has a 6 and 4 core radiator.He has used a fan shroud and clutch fan.Hopefully he will post his set up again so I can copy it too.

[kcjones]

Put 12v on the red prong of the voltmeter, touch the black prong to the body of the temp sending unit (not the connector!). You should show very little resistance. By moving the black prong of the meter to the connector, the resistance should shoot up if cold. If it only jumps a little while cold, your temp sensor isn't doing it's job: When cold the resistance of the sending unit should be high, when hot, resistance declines (no resistance, meaning a short, will shoot your guage up to 240+).

Guys, chime in here...that 6 cyl and stock radiator/"shroud" should keep this thing at about 180 idling in normal outside temperatures, right?

You shouldn't have to install a 4-core, shroud, and all that. There's something wrong with the reading, air flow, coolant flow, or ignition timing/carb mixture. You're on the right track, though.