Push rod question
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,074
From: Lansing MI
Safety Car
Joined: May 2001
Posts: 4,759
Likes: 1,647
From: Fairfax Virginia
I just want to add my .02 cents worth here if I may.
It sounds more like a EGR issue than a bent push rod. EGR's have a bad habit of making the engine hunt a bit for the idle and making a miss that just won't go away. On my car it was because the EGR Vacuum Solenoid had a loose vacuum line and it was defective anyway but it would hunt for idle speeds like a car with a bad vacuum leak. The EGR can affect your engine and is hard to detect unless you check the device manually and inspect/test it. In my case it came after a trip to get my emissions test here in Northern Virginia, the report that they gave me showed a very high NOX level which indicates frequently that you have a defective EGR system.
Do you have the Factory Service Manual for that particular year? It has a procedure for testing the EGR and determining what is defective. On my car the EGR passageways were clogged with Carbon deposits which required hours of cleaning, I replaced the EGR temp Sensor, the EGR valve and the Vacuum Solenoid to fix it properly.
If the car has older vacuum lines either replace them or cut the 1/2" off each end and make a secure connection to keep the vacuum leaks to a minimum. Any car as old as most of the C4's probably need new vacuum lines anyway. I had a bad leak at the Cruise Control device on the drivers side of my 1988 C4 Coupe.
I hope that you solve this issue easily and inexpensively! Have a great day!
It sounds more like a EGR issue than a bent push rod. EGR's have a bad habit of making the engine hunt a bit for the idle and making a miss that just won't go away. On my car it was because the EGR Vacuum Solenoid had a loose vacuum line and it was defective anyway but it would hunt for idle speeds like a car with a bad vacuum leak. The EGR can affect your engine and is hard to detect unless you check the device manually and inspect/test it. In my case it came after a trip to get my emissions test here in Northern Virginia, the report that they gave me showed a very high NOX level which indicates frequently that you have a defective EGR system.
Do you have the Factory Service Manual for that particular year? It has a procedure for testing the EGR and determining what is defective. On my car the EGR passageways were clogged with Carbon deposits which required hours of cleaning, I replaced the EGR temp Sensor, the EGR valve and the Vacuum Solenoid to fix it properly.
If the car has older vacuum lines either replace them or cut the 1/2" off each end and make a secure connection to keep the vacuum leaks to a minimum. Any car as old as most of the C4's probably need new vacuum lines anyway. I had a bad leak at the Cruise Control device on the drivers side of my 1988 C4 Coupe.
I hope that you solve this issue easily and inexpensively! Have a great day!
Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,074
From: Lansing MI
Thread Starter
Drifting
Joined: Dec 2012
Posts: 1,504
Likes: 73
From: Georgetown TX
That’s what we are going to check next, that and maybe a miss adjusted valve. He just replaced head gaskets a month ago. It had a bad gasket for some time but he was able to drive it still until it really let go. Sometimes when he started it the starter would not turn it over because of hydro lock, that’s why I’m thinking possible bent push rod
Last edited by mlm0; Oct 18, 2018 at 03:23 PM.
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Race Director
Joined: Oct 2008
Posts: 17,982
Likes: 1,074
From: Lansing MI
That’s what we are going to check next, that and maybe a miss adjusted valve. He just replaced head gaskets a month ago. It had a bad gasket for some time but he was able to drive it still until it really let go. Sometimes when he started it the starter would not turn it over because of hydro lock, that’s why I’m thinking possible bent push rod
