Engine Issue
Thread Starter
Heel & Toe
Joined: Jun 2015
Posts: 19
Likes: 0
Engine Issue
When I bought my 1980 Corvette, it was running great and now it seems to be having some trouble.
While sitting there parked my tach gauge is at 1200 RPM. When I engage the transmission, you can feel the car "clunk" and then "sit down." Basically the back end drops down and then idles down a little bit. I opened up the hood and now I have some smoke coming off the sides where it looks like oil burning off the side of the engine. The color is not white enough to just oil I am thinking coolant as well.
So new head gaskets? Carb relay? and ??
While sitting there parked my tach gauge is at 1200 RPM. When I engage the transmission, you can feel the car "clunk" and then "sit down." Basically the back end drops down and then idles down a little bit. I opened up the hood and now I have some smoke coming off the sides where it looks like oil burning off the side of the engine. The color is not white enough to just oil I am thinking coolant as well.
So new head gaskets? Carb relay? and ??
Team Owner
Joined: Jun 2000
Posts: 38,923
Likes: 1,481
From: Southbound
Cruise-In II Veteran
Advanced
Joined: Jun 2014
Posts: 58
Likes: 2
From: New Jersey
Sounds like you are describing some unrelated issues.
Here is where I would start looking.....
The smoke is likely leaky valve cover gaskets. they've been off for the orange paint.
The squat is normal, its brake torque acting on the rear suspension geometry. More noticeable with the idle a little high.
For the recent increase in idle speed, given the pictures that you provided, I would look for vacuum leaks.
The clunk, without knowing how harsh it is, is a tough one. It could be normal and related to the high idle, could be u-joints, could be differential. Again, without knowing how bad it is, it could be a non issue.
Good luck, start with the high idle and little oil leak.
Here is where I would start looking.....
The smoke is likely leaky valve cover gaskets. they've been off for the orange paint.
The squat is normal, its brake torque acting on the rear suspension geometry. More noticeable with the idle a little high.
For the recent increase in idle speed, given the pictures that you provided, I would look for vacuum leaks.
The clunk, without knowing how harsh it is, is a tough one. It could be normal and related to the high idle, could be u-joints, could be differential. Again, without knowing how bad it is, it could be a non issue.
Good luck, start with the high idle and little oil leak.
Racer
Joined: Mar 2013
Posts: 423
Likes: 25
From: Boca Raton Florida
I agree on starting with the valve cover gaskets. It looks like in one picture the front of the intake manifold is starting to leak oil as well but might be just run off from the valve covers. Also listen for a vacuum leak. While the car is running you can take your fingers and start pinching off any vacuum lines you see and if the idle drops that is the system that is leaking. Normal leakers are the headlight system, brake booster, and pcv systems to start with first. Squished or melted looking hoses are a good sign of a leak as well.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
Almost any well used vette will clunk at 1200rpm. In the pic, your choke is closed. If it's not opening all the way after warm up, you need to adjust it. On the passenger side of the carb you see a 2 inch black plastic cap held on by 3 small screws. Look closely at it and you'll see markings to close or open the choke. You'll want to loosen the 3 screws and turn it towards open 1 mark. Then test.
If it is opening all the way, you'll want to turn the idle down to 800. If it's idle ruff or stalling, try advancing the timing and see if that helps. Over the years many horminic balancer spin on the hub, throwing the timing marks off. Also chain stretch and just the factory settings where always never advanced enough.
If it is opening all the way, you'll want to turn the idle down to 800. If it's idle ruff or stalling, try advancing the timing and see if that helps. Over the years many horminic balancer spin on the hub, throwing the timing marks off. Also chain stretch and just the factory settings where always never advanced enough.
Safety Car
Joined: Mar 2007
Posts: 3,652
Likes: 49
From: Bridgewater nj
That last pic of the vacuum line looks like it's on it's last leg. I don't think it's your problem but it is something to look over all the vac lines. Slow headlight opening and high idle is usuall a sign of a leak somewhere in the miles of vac line we have!
Advanced
Joined: Apr 2015
Posts: 52
Likes: 0
From: Youngsville NY
The best way I have found to locate vacuum leaks is to use a spray can of carb cleaner. With the engine cold but running and a fire extinguisher on hand, spray SPARINGLY on each vacuum line where it connects to wherever. Listen for a change in the idle, if the engine starts to speed up or bog down, you have found a leaky vacuum line. Again SPARINGLY!!
Thread Starter
Heel & Toe
Joined: Jun 2015
Posts: 19
Likes: 0
Almost any well used vette will clunk at 1200rpm. In the pic, your choke is closed. If it's not opening all the way after warm up, you need to adjust it. On the passenger side of the carb you see a 2 inch black plastic cap held on by 3 small screws. Look closely at it and you'll see markings to close or open the choke. You'll want to loosen the 3 screws and turn it towards open 1 mark. Then test.
If it is opening all the way, you'll want to turn the idle down to 800. If it's idle ruff or stalling, try advancing the timing and see if that helps. Over the years many horminic balancer spin on the hub, throwing the timing marks off. Also chain stretch and just the factory settings where always never advanced enough.
If it is opening all the way, you'll want to turn the idle down to 800. If it's idle ruff or stalling, try advancing the timing and see if that helps. Over the years many horminic balancer spin on the hub, throwing the timing marks off. Also chain stretch and just the factory settings where always never advanced enough.
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Thread Starter
Heel & Toe
Joined: Jun 2015
Posts: 19
Likes: 0
Update
I am awaiting a spot to free up at Corvette Connection in Middleton, MA.
So till then I have been Youtube tinkering... So I have been doing what you guys have suggested. My headlights well the left light comes up much faster when I pinch off the vacuum line to the right side. You hear it leaking when you get up close to it.
I have oil leaking from the valve covers and oil around the spark plugs. When I started it up today my oil pressure was peaking around 80 PSI well running, normally I wouldn't see anything above 60.
My question is if I was to switch out or have the engine rebuilt, at what point do I need to upgrade the drivetrain?
So till then I have been Youtube tinkering... So I have been doing what you guys have suggested. My headlights well the left light comes up much faster when I pinch off the vacuum line to the right side. You hear it leaking when you get up close to it.
I have oil leaking from the valve covers and oil around the spark plugs. When I started it up today my oil pressure was peaking around 80 PSI well running, normally I wouldn't see anything above 60.
My question is if I was to switch out or have the engine rebuilt, at what point do I need to upgrade the drivetrain?