Two steps forward, one step back, hot motor help
Thread Starter
Racer
Joined: Jun 2020
Posts: 293
Likes: 107
From: Highland Village, TX
St. Jude Donor '21
Two steps forward, one step back, hot motor help
1974 L48 with 4 speed
So I've had my car for 2 weeks now and I've always thought the motor ran really hot. Even though the water temp gauge never got above 200. Put new plugs in to today and changed the oil first.
Next I checked the timing and found initial timing set to zero. Bumped that up to 14 and took total timing up to 36 degrees at 2500 RPM. Car ran so much smoother and had so much more power. But after running the motor for 10 minutes it would get really hot, like touching anything on the motor including air cleaner was too hot to touch.
Took it for a short drive and took the RPMs up to 4500 for the first time. Car still ran great but after parking it I noticed a puddle of green liquid under the car. Seems to be coming from the front of the water pump where it mates to the motor. Water pump doesn't seem to have any wobble or leaks anywhere but the gasket to the motor.
Thoughts? thermostat or water pump? Too much timing?
So I've had my car for 2 weeks now and I've always thought the motor ran really hot. Even though the water temp gauge never got above 200. Put new plugs in to today and changed the oil first.
Next I checked the timing and found initial timing set to zero. Bumped that up to 14 and took total timing up to 36 degrees at 2500 RPM. Car ran so much smoother and had so much more power. But after running the motor for 10 minutes it would get really hot, like touching anything on the motor including air cleaner was too hot to touch.
Took it for a short drive and took the RPMs up to 4500 for the first time. Car still ran great but after parking it I noticed a puddle of green liquid under the car. Seems to be coming from the front of the water pump where it mates to the motor. Water pump doesn't seem to have any wobble or leaks anywhere but the gasket to the motor.
Thoughts? thermostat or water pump? Too much timing?
Last edited by SVASSH; Jul 3, 2020 at 08:15 PM.
Race Director
Joined: May 2006
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Not clear how you first set initial to 14 and then set to 36 at 2,500. You either do one or the other.
To set total mechanical timing to 36 at 2,500 you would have to replace the factory advance springs with lighter springs.
Did you replace the springs?
Did you temporarily disconnect the vacuum advance when you set the 36?
You are sure the gasket is leaking and not a water pump mounting bolt? Unless the engine overheated there is no reason to suspect the thermostat.
To set total mechanical timing to 36 at 2,500 you would have to replace the factory advance springs with lighter springs.
Did you replace the springs?
Did you temporarily disconnect the vacuum advance when you set the 36?
You are sure the gasket is leaking and not a water pump mounting bolt? Unless the engine overheated there is no reason to suspect the thermostat.
Last edited by MelWff; Jul 3, 2020 at 08:32 PM.
Thread Starter
Racer
Joined: Jun 2020
Posts: 293
Likes: 107
From: Highland Village, TX
St. Jude Donor '21
Not clear how you first set initial to 14 and then set to 36 at 2,500. You either do one or the other.
To set total mechanical timing to 36 at 2,500 you would have to replace the factory advance springs with lighter springs.
Did you replace the springs?
Did you temporarily disconnect the vacuum advance when you set the 36?
You are sure the gasket is leaking and not a water pump mounting bolt? Unless the engine overheated there is no reason to suspect the thermostat.
To set total mechanical timing to 36 at 2,500 you would have to replace the factory advance springs with lighter springs.
Did you replace the springs?
Did you temporarily disconnect the vacuum advance when you set the 36?
You are sure the gasket is leaking and not a water pump mounting bolt? Unless the engine overheated there is no reason to suspect the thermostat.
HEI ignition with vacuum advance which I did plug when setting timing. Its coming out the bottom of the water pump right by a bolt..
Burning Brakes
Joined: Jun 2010
Posts: 1,165
Likes: 93
From: Bellmore NY
I would expect the engine to be physically hot to the touch after driving for 10 minutes, but hard to say how hot would be too hot here.
However coolant should be staying inside the engine no matter what. If it was coming out of the recovery tank, perhaps the tank was too full in the first place, but your seeing it at the pump.
If it was the thermostat housing, you'd see it on the manifold, whether rotted, loose, bad gasket etc. Are all clamps tight on each hose? Is it leaking out of the bottom of the pump?
Basically if you check everything, and can determine that the problem is the pump is leaking out of the front, or where it meets the block, then just change the water pump. Simple job.
Put on a good pump, and consider putting on a new clutch fan too.
However coolant should be staying inside the engine no matter what. If it was coming out of the recovery tank, perhaps the tank was too full in the first place, but your seeing it at the pump.
If it was the thermostat housing, you'd see it on the manifold, whether rotted, loose, bad gasket etc. Are all clamps tight on each hose? Is it leaking out of the bottom of the pump?
Basically if you check everything, and can determine that the problem is the pump is leaking out of the front, or where it meets the block, then just change the water pump. Simple job.
Put on a good pump, and consider putting on a new clutch fan too.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Can you stick your fingers in a cup of boiling water? I think not. Engine runs near (or at) 200 degrees all the time. Get/borrow/use an infrared temp sensor to check engine temp with another 'gauge'. If it isn't puking coolant and the gauges say it's below 200, quit worrying about it.
Thread Starter
Racer
Joined: Jun 2020
Posts: 293
Likes: 107
From: Highland Village, TX
St. Jude Donor '21
Can you stick your fingers in a cup of boiling water? I think not. Engine runs near (or at) 200 degrees all the time. Get/borrow/use an infrared temp sensor to check engine temp with another 'gauge'. If it isn't puking coolant and the gauges say it's below 200, quit worrying about it.
Race Director
Joined: May 2006
Posts: 18,734
Likes: 2,582
If you raise the engine speed to 3,000 does the timing go higher than 36?
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Thread Starter
Racer
Joined: Jun 2020
Posts: 293
Likes: 107
From: Highland Village, TX
St. Jude Donor '21
After putting the vaccum lines back on and setting the advance on the timing light back to zero the harmonic balancer was showing 14 degrees of advance at idle 850 RPM.
Last edited by SVASSH; Jul 3, 2020 at 11:58 PM.
Melting Slicks
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From: Dunedin NZ.
Race Director
Joined: Jul 2015
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From: SW Florida.
not a daily driver, i assume. don't buy or order a pump until you pull the current pump and check the gasket surface. also check the weep hole below the shaft. it can come out there and the fan will blow it all over. and yes HEI has springs. any dist with a vacuum can has centrif springs. too much advance will also run hot. double check your 36 degree total. without vacuum hooked up, run engine up until you see the 36. now, very quickly blip it higher while watching the light. you have to be sure it is done advancing with 36 total.
Race Director
Joined: Mar 2017
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From: Virginia
As I've done many times before, I'd strongly suggest you email @lars on this forum for his timing papers. The stock HEI springs may not stop advancing until 4000 to 4500 rpm, until you change them. I use one light, one medium, from a kit to get max mechanical advance at 2800 or so. If you have the means to do so, picking up a digital timing light that has an RPM readout (and dialback), can save you a lot of grief and guessing. An IR thermometer, shot at the upper radiator hose (mine doesn't like reflective metal), is likely the best gauge of the operating temperature of your engine.
Also, until you confirm that it is not the case, whatever vacuum advance can you have may have more than 12 degrees of advance. This can be corrected (suggestions are in @lars' papers). It should be connected to manifold vacuum.
After I tuned both cars, my engines ran much better, and cooler. This was evident under the hood (IR thermometer), and on the sidepipe exhaust.
Also, until you confirm that it is not the case, whatever vacuum advance can you have may have more than 12 degrees of advance. This can be corrected (suggestions are in @lars' papers). It should be connected to manifold vacuum.
After I tuned both cars, my engines ran much better, and cooler. This was evident under the hood (IR thermometer), and on the sidepipe exhaust.
Burning Brakes
Joined: Jun 2020
Posts: 881
Likes: 113
kinda new to this ?
Sometimes, the so called "dial back" timing lights do Not flash at the degree-setting selected by user.
Sometimes, that old harmonic balancer / torsional damper's outer ring "slips" rendering the TDC "Groove" out of position
Sometimes, the so called "dial back" timing lights do Not flash at the degree-setting selected by user.
Sometimes, that old harmonic balancer / torsional damper's outer ring "slips" rendering the TDC "Groove" out of position
Thread Starter
Racer
Joined: Jun 2020
Posts: 293
Likes: 107
From: Highland Village, TX
St. Jude Donor '21
Checked it again tonight anti freeze is coming from under the water pump likely the weep hole. New water pump in my future probably replace the thermostat also since I’ll be draining it.
It’s a shame since the car starts so easily now with the timing set and runs so great. Water pump looks to be the only thing not new on the engine. Murphy’s law.
Last edited by SVASSH; Jul 4, 2020 at 07:14 PM.
Is my vette stock?? HAHA
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you may just have a bad gasket. If you are sure its coming out from the gasket/ engine interface and not he top of the hose or the weep hole. Check the cheapest easiest things ot fix / replace first
Thread Starter
Racer
Joined: Jun 2020
Posts: 293
Likes: 107
From: Highland Village, TX
St. Jude Donor '21
Ok finally got back to this today. Swapped out the water pump and thermostat just for good measure, new 50/50 coolant. Running great again but more importantly not leaking fluid. Interesting thing is I think it was leaking from the water pump weep hole but also from the top drivers bolt which on mine is a bolt with a stud on the end for the alternator adjusting bracket. I noticed the top drivers bolt with the stud was a bastard to get out and the end of the threads looked pretty crunched. When reassembling I could not get that same bolt stud to seat properly. I had to cut about 3/8" off the end to get it to seat properly when tightening. I think the problem may have been the bolt stud being too long and the gasket finally gave out. Also put a 195 thermostat in and the one I took out was marked 160.
Double checked the timing and I am all in at 36 degrees timing at about 3000 RPM, no rise from there to 4500 RPM. Car runs strong and water temp rises quick to ~200 and stays there.
Thanks for all the advice.
Double checked the timing and I am all in at 36 degrees timing at about 3000 RPM, no rise from there to 4500 RPM. Car runs strong and water temp rises quick to ~200 and stays there.
Thanks for all the advice.