My blazer has a 350 motor that runs really well when it's warm but seems to have the symptoms of a vaccum leak. It chugs when it's cold and when it's warmed up the exhaust manifolds occasionally glow(i've been told that is a byproduct of a vaccum leak), it also runs a little hot. Could these be cause by a leaky intake manifold? It is pretty wet around there but i'm pretty sure that's from the valve covers. Should I just replace the valve cover gaskets and see if that stops the leaks? There are no vaccum leaks externally which makes me think it could be in the manifold. Tanks a lot for any and all help.
CK5
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Should I?
- Thread starter 82_k5
- Start date
sled_dog
1 ton status
take a can of carb cleaner or starting fluid while the truck is idling. Spray around the edge of the manifold. If your idle changes at all you have found a vaccum leak. I'd recommend changing the cover gaskets and cleaning up the motor. I'm anal about cleaning my junk, I like to know exactly where a leak is coming from should one develop.
I just reread, so do you think the inner oil side of the intake gasket is where the leak would be? I mean thats possible but then why would it be wet or dirty up top? Do as I said and also replace the valve cover gaskets.
Oh yeah and the distributor is the hardest part of the intake swap. And thats pretty simple if you don't over think it. Raise to TDC drop her in pointing to number 1 and sinch it all up, time it when you get her running.
I just reread, so do you think the inner oil side of the intake gasket is where the leak would be? I mean thats possible but then why would it be wet or dirty up top? Do as I said and also replace the valve cover gaskets.
Oh yeah and the distributor is the hardest part of the intake swap. And thats pretty simple if you don't over think it. Raise to TDC drop her in pointing to number 1 and sinch it all up, time it when you get her running.
I don't know a whole lot about vaccuum leaks but it does sound like the byproduct of a lean mixture.
As for the R&R on the intake gasket. It's not bad depending on what kind of carb and smog setup you have. On my Cali '85 with the CCC setup it was a nightmare. If you have a simple engine under the hood then just pop off the vaccuum and fuel lines, and the distributer. Be carefull to not let pieces of gasket fall into the engine as you clean it off the heads.
Also, make sure the 4 bolts that hold down your carb are tight. That is the most common spots for vaccuum leaks. You can spray carb cleaner around the intake and bottom of the carb to see if the engine idle changes at all. If it does you have a vaccuum leak and it is where you just sprayed.
As for the R&R on the intake gasket. It's not bad depending on what kind of carb and smog setup you have. On my Cali '85 with the CCC setup it was a nightmare. If you have a simple engine under the hood then just pop off the vaccuum and fuel lines, and the distributer. Be carefull to not let pieces of gasket fall into the engine as you clean it off the heads.
Also, make sure the 4 bolts that hold down your carb are tight. That is the most common spots for vaccuum leaks. You can spray carb cleaner around the intake and bottom of the carb to see if the engine idle changes at all. If it does you have a vaccuum leak and it is where you just sprayed.
dirtwarrior17
Banned
if its leaking water....
new gaskets and some rtv and your all good.
don't know about the manifolds glowing.
new gaskets and some rtv and your all good.
don't know about the manifolds glowing.
cats glowing = too rich
manifolds glowing = possible lean condition
cats being plugged will make manifolds glow... late ignition too...
intake leak will lean ya out and do this. starting fluid will find vacuum leaks instantly, just be careful about that with the glowing manifold issue....
foolish not to do valve covers if their leaking. simple and cheap.. cover carb and dizzy with plastic bags. degrease, clean and rinse intake. blow dry. i too am anal about that stuff
then do your vc gaskets before you mess with the intake...
manifolds glowing = possible lean condition
cats being plugged will make manifolds glow... late ignition too...
intake leak will lean ya out and do this. starting fluid will find vacuum leaks instantly, just be careful about that with the glowing manifold issue....
foolish not to do valve covers if their leaking. simple and cheap.. cover carb and dizzy with plastic bags. degrease, clean and rinse intake. blow dry. i too am anal about that stuff
then do your vc gaskets before you mess with the intake...dirtwarrior17
Banned
true true... lean will definitly make her run hot.
had a ranger gome in the shop one time and was same problem . found distributer out 180* and real pain to get to so just moved the wires 180* on cap fixed it with no more problems.
