Hey everyone, I am having some major problems with my engine. I have a 305 TBI "LO3" with 113k miles on it. After I changed my intake manifold (believe me I installed it right, it's my second time) I had some major problems. First of all my idle is at about 2000 rpm. Ok, I thought it was the timing but it is properly set. But, that isn't my only problem I seem to be burning antifreeze and oil. The antifreeze is disappearing really fast, and the oil is burning but not that quick. The car seems to drive fine other than those facts, but it's kinda scary. I thought it might be a head gasket, but I was told that this would make your temperature go up, and mine stays nice and cold (around 130). Another thing it does, is when I'm sitting at a red light my rpms will slowly drop almost 1000rpm. The engine will also, shake (like it's backfiring). I have no idea what is wrong, but any ideas would be helpful. Thanks.

-Matt

 

You may have a spun balancer, causing the timing to be set improperly.

 

Well, I don't think it's a spun balancer. The engine timing is near perfect. I'm just wondering what could cause oil and antifreeze to get into your combustion chamber.

 

A sensor?? Not meaning its bad, but maybe the sensor can't "handle" your mods.

 

may be a crack in the block. does the oil look like a chocolate milkshake?? It could also be a blown head gasket.

 

Both the oil and coolant can come from the intake manifold. An accompanying vacuum leak could cause the other problems.

It isn't outside the realm of possibility that you got a bad manifold. I got a Weiand Action+ for the 396 that was improperly machined. I think it was supposed to be scrapped (not all of the mount bolt holes were drilled, for instance), but made it to shipping anyway. Turns out the mount surfaces to the heads were not in the proper planes, leaving a gap under the runners on one side of the intake. I used a quart of oil in the first 50 miles (believe me, you could tell it was burning oil!).

Coolant is a bit harder to do, practically takes a crack between the coolant passage and intake runner. But, still possible.

Since these problems started with the intake change (am I assuming too much here?), it seems reasonable to start looking there for the cause.

 

Well, I already changed my intake manifold, and it is sealed fine, the gaskets are seated properly and everything checked out good. I just changed my oil, about 2 days ago, and it hasn't changed colors yet. My coolant has gone down about a gallon in 2 days (really a gallon). I have no vacuum leaks. I think this must leave either a blown head gasket, cracked block, or cracked piston. But is there anyway to tell between these just by symptoms, or will I just have to take my engine apart? Thanks

-Matt