350 Vortec

First of all, Merry Christmas to everybody out there.
now for my problem, I have a 350 vortec engine in a 93 GMC 3500. The engine starts, idles smoothly and moves the truck, but on taking a compression test I got 160 +/- psi on the driver's side. on the passenger's side, I get 0 readings on all four cylinders. I haven't had much experience working on vortec engins, so I'm at a loss. I would appreciate any help I can get on this.
Thank you Peace and Blessings,
Chico


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I'm interested in hearing the other responses to your problem. Have you pulled the valve cover? I'm wondering if a bad head gasket on that side has rusted out your valve train or something to that effect. Water would have had to of gotten into all of the cylinders which is hard to believe. What did the plugs look like when you took them out to do the compression test?

Not doubting your results but are you 100% on the no compression? I'd do a check back on the "good" side to see if there's something up w/the gauge that happened between the two sides.

What were the circumstances or symptoms that led you to do the compression test in the first place? Was the engine ever running correctly while you had it? Was it overheated or did it suddenly lose power while you were driving, or ?

Mhernandez,

I am with cobalt327! Check the gauge! If the engine runs fine, it can not have "0" compression on four cylinders.
I think something happened to the gauge. Not sure which type you have but the first place I would check is the schrader valve at the end of the hose. This is the heart of a compression gauge. It allows compression air into the gauge but will not let it out until you depress the center pin. Works something like a valve stem on a tire EXCEPT on a tire you must depress the pin to allow compressed air into the tire.

Good Luck And Merry Christmas back at you!

Scholman

I agree, sounds like a bum gauge. Also keep in mind. Your engine is a "Vortec" engine but only in name. GM started using the name in the 80`s. However the TBI engines as we call them such as what came in your vehicle is no different internally than the carbed engines of the past. What we refer to real Vortec engines are the 1996 and up as multi port injection was used and TBI was discontinued.

Thanks for the quick replies, I remember one time trying to do a compression test on an engine, I was getting 0 readings and when I checked the gauge the valve had stuck in the open position, so it wasn't holding any air. Te engine is at a friend's house and he did the test. I will get with him on that gauge and we'll try a different one to see if the results change. I'll post the findings, so we'll all know what is going on.
Hope everyone has a very Merry Christmas
Peace and Blessings,
Chico

I checked the shrader valve on the gauge and it works fine. Took three tests on the engine with the same results. Plugs were clean when removed. Engine was overheated once when the thermostat stuck.
On another thread , the wiring harness going to the transmission I believe its a 4l80 or 4lE80 will it work on a 305 engine? how do we work out the wiring harness The 305 and tranny will be going into a 90 half ton

Just wanted to clear up on what I posted before on the transmission problem.
My friend has a 91 chevy half ton running a 305 engine with a five speed manual trans. The GMC with the 350 engine has the automatic. He wants to pull the automatic from the GMC with the 350 and put it in the 91 with the 305. he doesn't know how the wiring harness on the automatic will affect it when installed in the 91

mhernandez,

The 91 doesn't know what engine is powering it. Just transfer all the sensors from the downer to the engine and everything will work.

Scholman

I'm not changing the engine in the 91, it came factory stock with the 305. What I'm putting into it is the automatic trans out of the GMC with the 350. The wiring harness on the automatic is the problem because it's replacing a five speed standard with no wiring harness.

If the tranny is a 4L60E it will not work without the factory computer in 1994 and up vehicles or without a aftermarket unit to control it which costs a arm and a leg. The 4L60E is fully electronic. The valves in the valve body are operated by solenoids. However, if the tranny is a 700R4 it can be used without a computer. a 700R4 will require the correct detent cable in correct adjustment as well as a lockup kit. You can go without the lockup functioning but only if you install a aftermarket tranny cooler, which I would do regardless.

I have another question about the transmission. The automatic came out of a 93 GMC 3100 running a 350 engine. He wants to take the tranny out of the jimmy and put it into a 91 chevy half ton running a 305 and a five speed standard. Will the tranny out of the jimmy with the 350 bolt up to the chevy with the 305? Will the flex plate off of the 350 bolt onto the 305?