Problems after intake manifold gasket replacement
02-28-2017, 05:48 AM
#1
Heel & Toe
Thread Starter
Problems after intake manifold gasket replacement
EDIT: well, the smoke has subsided after a hard, but steady idle. Think it was just residue. And I've pin pointed the leak down to the bottom middle of the driver side runners. Sounds like it's coming from the cold start right there. Doesn't look like it's the manifold hissing, as there is no coolant seeping through the new gaskets. Could've been that I forgot to torque those down (rookie mistake) or something simple as that. Thanks guys for your help, I'll update again when back on the road.
Hey guys, I'm new here, this is my first thread. That said I've been reading up on here for months ever since I got my 1987 4+3 Vette. And I love it to death. Anyways, a couple weeks ago I blew my intake manifold gasket. Car still ran fine, but was leaking coolant horribly. I spent about a week taking it apart (I'm a novice, this is my first big project), and two nights getting it all back together. I had replaced a few vaccum lines here and there while I was down there as well. But now I've got a problem I've been tripping over for days. I got the distributor all in to where I can get her to idle. But, there is a MASSIVE hiss coming from the intake, and there is white, plastic smellimg smoke coming from what looks like the exhuast manifold and cats. EGR valve is working properly and I've got everything back together perfectly. Again, at a complete loss here. Anyone got any ideas? Anything helps. Thanks.
Hey guys, I'm new here, this is my first thread. That said I've been reading up on here for months ever since I got my 1987 4+3 Vette. And I love it to death. Anyways, a couple weeks ago I blew my intake manifold gasket. Car still ran fine, but was leaking coolant horribly. I spent about a week taking it apart (I'm a novice, this is my first big project), and two nights getting it all back together. I had replaced a few vaccum lines here and there while I was down there as well. But now I've got a problem I've been tripping over for days. I got the distributor all in to where I can get her to idle. But, there is a MASSIVE hiss coming from the intake, and there is white, plastic smellimg smoke coming from what looks like the exhuast manifold and cats. EGR valve is working properly and I've got everything back together perfectly. Again, at a complete loss here. Anyone got any ideas? Anything helps. Thanks.
Last edited by Justicethelamb; 03-01-2017 at 02:57 PM.
02-28-2017, 02:46 PM
#3
Heel & Toe
Thread Starter
Sweet, looks like it's black like mine too! I'm not sure about temp, I didn't want to keep on pushing it because of the issues, and it was idling really hard.
02-28-2017, 03:11 PM
#4
Le Mans Master
Get a length of small diameter hose (plastic or rubber doesn't matter). Use this as a stethoscope. Place one end at your ear and use the other end to move around the intake manifold.....your looking for the hissing sound you described. Also check all your hoses to see if they are all connected. Don't forget the large hose that goes to the brake booster.
You will often drop small pieces of gasket material from taking things apart onto the exhaust manifold or drip oil onto the manifold. This will quickly burn off as you run the engine. Just watch things to be sure you don't have flames anywhere.
You will often drop small pieces of gasket material from taking things apart onto the exhaust manifold or drip oil onto the manifold. This will quickly burn off as you run the engine. Just watch things to be sure you don't have flames anywhere.
02-28-2017, 03:45 PM
#5
Heel & Toe
Thread Starter
Get a length of small diameter hose (plastic or rubber doesn't matter). Use this as a stethoscope. Place one end at your ear and use the other end to move around the intake manifold.....your looking for the hissing sound you described. Also check all your hoses to see if they are all connected. Don't forget the large hose that goes to the brake booster.
You will often drop small pieces of gasket mate5rial from taking things apart onto the exhaust manifold or drip oil onto the manifold. This will quickly burn off as you run the engine. Just watch things to be sure you don't have flames anywhere.
You will often drop small pieces of gasket mate5rial from taking things apart onto the exhaust manifold or drip oil onto the manifold. This will quickly burn off as you run the engine. Just watch things to be sure you don't have flames anywhere.
02-28-2017, 06:11 PM
#6
Drifting
Use a smoke test to determine where your leak is. Look on YouTube. There are lots of examples there. You can even use a cigar instead of making your own smoke machine. I made mine out of a glass jar
03-01-2017, 01:56 AM
#7
Heel & Toe
Thread Starter
03-01-2017, 08:52 AM
#8
Team Owner
Where in the intake? If the timing is wrong, the IAC might be trying to compensate and hence the hiss. My car hisses like no tomorrow when the IAC opens. Your IAC housing could be dirty and not flowing like it should and make the IAC open more hence the hissing.
Where exactly is it hissing from? If it is the front of the TB, that is normal.
03-01-2017, 01:58 PM
#9
Heel & Toe
Thread Starter
I hope you get it running and set the timing since that can affect other things.
Where in the intake? If the timing is wrong, the IAC might be trying to compensate and hence the hiss. My car hisses like no tomorrow when the IAC opens. Your IAC housing could be dirty and not flowing like it should and make the IAC open more hence the hissing.
Where exactly is it hissing from? If it is the front of the TB, that is normal.
Where in the intake? If the timing is wrong, the IAC might be trying to compensate and hence the hiss. My car hisses like no tomorrow when the IAC opens. Your IAC housing could be dirty and not flowing like it should and make the IAC open more hence the hissing.
Where exactly is it hissing from? If it is the front of the TB, that is normal.
I don't know. Hopefully not the manifold leaking again, don't wanna have to jump in there. But if that's what it comes down to, I suppose I'll have to! Also, do you have to unplug the IAC to correctly time it?
Last edited by Justicethelamb; 03-01-2017 at 02:01 PM.
03-01-2017, 03:07 PM
#10
Le Mans Master
No, you don't have to unplug the AIC. You unplug the EST wire which is a single brown (might have a white stripe...it has been awhile) wire that is next to the wiper motor. Set your timing and plug the wire back in. NOTE: you will set a code 41 I believe when you unplug the wire. Just disconnect the battery negative terminal for about a minute and that will clear the codes.
03-01-2017, 03:24 PM
#11
Heel & Toe
Thread Starter
No, you don't have to unplug the AIC. You unplug the EST wire which is a single brown (might have a white stripe...it has been awhile) wire that is next to the wiper motor. Set your timing and plug the wire back in. NOTE: you will set a code 41 I believe when you unplug the wire. Just disconnect the battery negative terminal for about a minute and that will clear the codes.
Last edited by Justicethelamb; 03-01-2017 at 03:24 PM.
03-01-2017, 04:03 PM
#12
Team Owner
I thought it was coming from the EGR originally, but I checked that and it was completely normal. No leaks and was holding vaccum. Sounds like it could be coming from the bottom end of the runner? I don't know. Hopefully not the manifold leaking again, don't wanna have to jump in there. But if that's what it comes down to, I suppose I'll have to!
Also, do you have to unplug the IAC to correctly time it?
I don't know. Hopefully not the manifold leaking again, don't wanna have to jump in there. But if that's what it comes down to, I suppose I'll have to!Also, do you have to unplug the IAC to correctly time it?
It's hard to say. The IAC is at the bottom of the TB. You do not need to disconnect the IAC to time the motor. Having the motor timed correctly makes it easy to set the IAC. Also when you are doing the IAC you can see if you have any leaks