Chevy Nova Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
509 Posts
Discussion Starter #1
Hey guys,

I went for a cruise yesterday & lost my fan/wp/alt belt. I have no idea how long it was hot or how hot it got...I know that the temp gauge was buried by the time I noticed.

I put a new belt on & checked my fluids & fired it up. Now it wont idle, if I hold the throttle at 2000rpm it will fluctuate between 1500-2000. Anything under 2000 & it creeps down until it dies...unless I pedal it.

What am I looking at for possible issues? Where should I start?

Thanks!
 

·
Registered
Joined
·
234 Posts
There's a good chance you're looking at a popped head gasket or two. Do a compression check to find out for sure. If (or maybe when) you find that to be the problem, then you need to also have your heads checked for warpage. Any decent machine shop can resurface them to true them up if they're warped. How is your oil pressure, and is it knocking any in the bottom end? If pressure is low (determine that before you tear the heads down), then you will probably just need to go ahead and do a rebuild on the short block as well. Not much more if you already have the engine out.

Let us know what you find out, and good luck!
 

·
Registered
Joined
·
509 Posts
Discussion Starter #3
Oil pressure is the same as always & I do not here any knocking for the bottom end. I will run a compression test & see what I get, what range am I looking for on my gauge? Also, do valve springs get weak when overheated?

Thanks Again!
 

·
Registered
Joined
·
771 Posts
Depends on compression ratio but Id say 150 and above would be good comp. Depends on the motor though. But if the head gasket is blown than itll be like 100 or less compression so.....
 

·
Premium Member
Joined
·
4,125 Posts
Oil pressure is the same as always & I do not here any knocking for the bottom end. I will run a compression test & see what I get, what range am I looking for on my gauge? Also, do valve springs get weak when overheated?

Thanks Again!
Any differential of more than 10% between cylinders is enough to cause suspicion that something is wrong. If you've blown a head gasket you'll likely notice a MUCH bigger difference than that. The first thing you'll notice though will be when you pull the plugs. They'll probably be wet with water, not fuel!

Good luck. Let us know what you find.
 

·
Registered
Joined
·
3,849 Posts
If you werent spewing liquids from the rad you may have been hot, but not to failure. Check yer catch can and make sure to refill the rad too if it dumped.

For the idle issue Im sorry, no help here. Um, pull a couple plugs and read them. Will tell alot. JR Oh, and drop the oil and check it Durr... Ok, one more thing. Seems to me, if the engine got really hot the lifters may have scrubbed due to starvation. If you get to the point of lifting the heads check the lifters for any galling.
 

·
Registered
Joined
·
509 Posts
Discussion Starter #7
OK I still need to buy a compression gauge but I did a little playing around today since I got back from vacation.

I borrowed a harbor freight leakdown tester from a guy & tried to used it to read % of leakage....the tool is a POS & wont read right so I ended up just using the short hose to pressure up each cylinder at about 40PSI. I listened to the rad/ext/carb/dipstick & all I could hear was the dipstick...which I believe some leakage pas the rings is marginally exceptable.

Anyway..I finished all that & started the car & pedaled it until it got up to operating temp. It smoothed out almost completely. I took it out & ran it pretty hard with only a minor intermitent low RPM misfire. Since, I let it cool off & started it back up with the same probs as before..whatever it is smooth out with the engine at temp...

Any thoughts?

THANKS!
 

·
Registered
Joined
·
509 Posts
Discussion Starter #8
OK today I got the engine to operating temp & ran a compression test. The cylinders range from 145-150. I also checked the oil again & it is normal as well as the coolant. The plugs all have the same clean burn as always.


???????

What the heck temp wise could have happened that would cause these symptoms? I have run out of ideas...any input guys??

Thanks!
 

·
Registered
Joined
·
3,859 Posts
Your idle issue sounds like a vacuum leak, possibly caused by the hot temps maybe cracked a hose, your pcv valve or your intake gaskets.
 

·
Registered
Joined
·
509 Posts
Discussion Starter #10
It does act like a vacuum leak. I checked the carb spacer & gaskets but thats it. Whatever it is must partially seal up after it reaches engine temp since it tends to smooth out when its warmed up, that part still boogles me!?!?

I'll check it out...thanks!!!
 

·
Registered
Joined
·
170 Posts
You have alum heads?? May not be warped that bad and once the head warms up it fills the gap.... Just a slightly drunk thought(hit the dirt track tonight)
 

·
Registered
Joined
·
509 Posts
Discussion Starter #12
OK, I really cannot find any typical issues that jump out at me that would be symptoms of a overheating. I'm really leaning towards a carb issue.

Tonight I warmed it up & drove it again. It has a constant surge/hesitation at cruise & idles pretty crappy. Any tips ? I have a Holley 750 4160...thanks!
 
1 - 12 of 12 Posts
Top