Cooling issues

[68Datsun510]

Hello folks, having an odd cooling issue. Mine you, this predates the failed pump from Canby! LOL

 

Driving, I have no problem whatsoever maintaining proper temp. The only issue is sitting idling, or stop and go traffic. The temp remains at 195 for a few minutes, then steadily climbs. Predictable as the sunrise.

 

Im running a 3 row factory radiator with a new core, and foxed 4 blade fan system on the pump, and 50/50 coolant/water wetter. Nissan thermostat.

 

Ideas?

[ggzilla]

Usually it is an airflow problem. Poor fan placement, wrong fan size, air escaping around the radiator

 

What is a foxed fan?

[68Datsun510]

FIXED, my bad :P The factory style 4 blade fan.

[ggzilla]

With cooling systems, you have Air Flow and you have Coolant Flow.

 

Is the fan close enough to the radiator -- within 1.5" of the core? Shroud in place? Any gaps at top,bottom,or sides between the radiator and core support?

[datzenmike]

Loose or glazed fan belt.

Dirty exterior fins on rad.

Plastic bag or leaves blocking air flow through the grill

Missing shroud.

Retarded ignition timing.

Lean idle mixture.

[Ranman72]

what mike said but shroud and air pull first

try putting a high volume fan in front of it and see what happens

I have a large fan we can set on a chair and try it at my house if you like

[bonvo]

ditch the factory fan and go electric the factory fans just arent enough after all these years hell they were just barly enough when new

[ggzilla]

I have solved many cooling problems by replacing aftermarket electric fans with stock engine-driven fans.

 

but there's no question that a good electric fan can do a very good job.

[banzai510(hainz)]

question is was it doing it before in the same climate temp????? Like was it doing this last year in summer? If not I think soemthing is going out.

 

Im not again elecric fans but masking a head gasket proplem isnt going to fix it either.

 

these car went 40years w/o a electric fan.

[I'm BLUE]

This is going to sound funny.

 

There is soooo much rust scales/buildup in the engine blocks that it causes a poorer cooling situation.

I opened my block drain and freeze plugs on my l-series engines then pressure washed them out for 20 minutes or so ecvery which way possible/flushed radiator/new hoses/t-stat/flush radiator/check water pump. Temp gauges ran 100% perfect even in 95 degree rush hour traffic (idle or cruise) even now ...

 

Check the tightness of your valves as routine slowly.( better loose than tight)

Check heat range of spark plugs.( not likely but helps if there is another problem)

Like mike said check mixture ( o2 sensor and multimeter or air/fuel gauge )

Machine shop around the corner from my place .. said that these heads are very prone to spider web cracking in water jackets passages .. by electrolysis especially if not taken care of.

 

Check muffler ... a partially blocked/old one will do the same ... it did to me on my blue 240z when it was first purchased.

 

I highly doubt it's any of your cooling system components in this case... more so they are masking another issue

[68Datsun510]

With cooling systems, you have Air Flow and you have Coolant Flow.

 

Is the fan close enough to the radiator -- within 1.5" of the core? Shroud in place? Any gaps at top,bottom,or sides between the radiator and core support?

 

All factory setup, fan, shroud, rad, etc. Gaps are all minimal.

 

Loose or glazed fan belt.

Dirty exterior fins on rad.

Plastic bag or leaves blocking air flow through the grill

Missing shroud.

Retarded ignition timing.

Lean idle mixture.

 

Belt is new

rad is clean

no debris

shroud in place

timing is 15btdc

idle mix is stoich/rich

 

what mike said but shroud and air pull first

try putting a high volume fan in front of it and see what happens

I have a large fan we can set on a chair and try it at my house if you like

 

This fan setup cools Dave Witts cars, all of them with no issues, dont think its fan related...

 

ditch the factory fan and go electric the factory fans just arent enough after all these years hell they were just barly enough when new

 

I know too many cars that work just fine on a factory fan with a KNOWN GOOD RADIATOR. Clogged up old rad and a fixed fan will not work lol

 

I have solved many cooling problems by replacing aftermarket electric fans with stock engine-driven fans.

 

but there's no question that a good electric fan can do a very good job.

 

I have a 12" pusher on there too... =/

 

question is was it doing it before in the same climate temp????? Like was it doing this last year in summer? If not I think soemthing is going out.

 

Im not again elecric fans but masking a head gasket proplem isnt going to fix it either.

 

these car went 40years w/o a electric fan.

 

Last year, no problems. Until the fan clutch went out lol...

No head gasket issues, no water in oil or oil in water, block is o-ringed, no leaks.

 

This is going to sound funny.

 

There is soooo much rust scales/buildup in the engine blocks that it causes a poorer cooling situation.

I opened my block drain and freeze plugs on my l-series engines then pressure washed them out for 20 minutes or so ecvery which way possible/flushed radiator/new hoses/t-stat/flush radiator/check water pump. Temp gauges ran 100% perfect even in 95 degree rush hour traffic (idle or cruise) even now ...

 

Check the tightness of your valves as routine slowly.( better loose than tight)

Check heat range of spark plugs.( not likely but helps if there is another problem)

Like mike said check mixture ( o2 sensor and multimeter or air/fuel gauge )

Machine shop around the corner from my place .. said that these heads are very prone to spider web cracking in water jackets passages .. by electrolysis especially if not taken care of.

 

Check muffler ... a partially blocked/old one will do the same ... it did to me on my blue 240z when it was first purchased.

 

I highly doubt it's any of your cooling system components in this case... more so they are masking another issue

 

Not funny, a potential real issue in old ass engines. Mine was rebuilt 1.5 years ago. Completely cleaned and flushed. Valves are in spec. BP6ES plugs, head was just

rebuilt/tested by Rebello Racing during rebuild.

 

 

So there are only two possibilities, my radiator isnt what i was told, which isnt a surprise, came to find the same shop "re cored" my dads mustang radiator, claimed it was a brand new 3 row core. Car leaked coolant from rad, had another shop look, no re core, no work, nothing. Same rotten 2 row. He painted it and charged my dad $450. Same guy built my radiator a few years before....

 

OR

 

The thermostat got lazy/sticking.

 

So, starting cheap. Replacing the t stat, then ill have another shop examine the core.

[datzenmike]

timing is 15btdc

 

 

Stock L series timing is 12 degrees.

[68Datsun510]

Its not stock ;)

 

Recurved distributor, cam, high compression.

[Dat510_Chris]

Maybe a silly question but are you actually over heating or just going by the temp gauge? stock dash temp gauge or aftermarket installed gauge?

[datzenmike]

Hmmmm even more reason to run less timing. Hell try it, you never know it could be something simple and easy to put back.

[68Datsun510]

Doesnt idle too well with less advance. Ill experiment. ANd i do plan on verifying the gauge accuracy. I have an autometer electrical gauge.

[Dat510_Chris]

Doesnt idle too well with less advance. Ill experiment. ANd i do plan on verifying the gauge accuracy. I have an autometer electrical gauge.

 

I have had my gauge start acting up, drive 2 hours with it in the red telling me my engine should be exploding only to release the pressure and having it do the smallest little pfft of steam.

[68Datsun510]

BTW Datzenmike, no pinging present at all.

[68Datsun510]

Proper fitting shroud and new thermostat and issues seem to be gone!

[Laecaon]

Shrouds do a lot. I have seen many overheating issues go away with a shroud.

[68Datsun510]

Had a shroud on there, but it was hogged out for a clutch fan, but had a factory 4 blade in there.

[datzenmike]

A lot of old Datsuns have a metal splash shield under the rad and front of the motor. It's hard to get at the lower rad hose and the alternator so it's the first thing removed when under there. I don't know if the 510 had one but my 710s do.... well did. This would also act as a kind of shroud and cause a low pressure area just above it just behind the rad.

[68Datsun510]

I still have it installed for that very reason

[datzenmike]

Mine are off but saved... somewhere. It doesn't get that hot here anyway but further south like you are, everything helps.

[510-Trevor]

Hello folks, having an odd cooling issue. Mine you, this predates the failed pump from Canby! LOL

 

Driving, I have no problem whatsoever maintaining proper temp. The only issue is sitting idling, or stop and go traffic. The temp remains at 195 for a few minutes, then steadily climbs. Predictable as the sunrise.

 

Im running a 3 row factory radiator with a new core, and foxed 4 blade fan system on the pump, and 50/50 coolant/water wetter. Nissan thermostat.

 

Ideas?

Air gaps around the rad and the lower shroud will only effect temps at speed. Higher temps while idling are more indicative of a bad t-stat, incorrect timing or too lean of idle mixture. Like you've mentioned, start by testing the t-stat, throw it in a pot of boiling water and see what happens. If it works, move on to timing, then your idle mixture.