Hey All,

I saved up a bit and finally got a whack of work done on my '94 I6.

It was a mess when I got it. It drove like an old tractor, but new power steering lines and pump, new shocks, brakes, bearings, brake lines, tires and alignment took care of the ride. I got Michellin X-Ice tires... so far the best winter tires I've ever had. Wow. I can't begin to describe the difference. Before it would feel unstable at 90kph (55mph). Now it feels stable, and can reach 140kph (85mph) with no vibration. So brakes steering and suspension are all ok.

I also put on a new rear gas tank, new lines, cleaned the fuel injectors and finally got the fuel filter changed. My mechanic fixed the stuck fuel filter by splicing into the gas line and putting new 3/8" (not 5/16") ends on them, and attaching a different fuel filter. He gave me the part # for the new type of filter. It's smaller than the original, and I don't think it will be a problem, but I would like to be sure. I looked it up and it's designed for several 90-92 GM vehicles, the largest of which is a 3.1l engine. Chev Beretta, Corsica, and Pontiac Tempest. Is this going to cause problems? Should I be changing it more often?

The new filter has made a huge difference. First, the screaming pump noise is gone, it always starts first try, and the acceleration and top speed are all much better. Second, the gas consumption has at least doubled. I may be looking at 200 miles/tank.

I'm broke again for at least a month, but I'm already wondering what to go at next. Now that the pump is quiet, I can hear it's knocking heavily. It runs cold (or the thermometer is off), and the volt meter is always on 18. I've already replaced some of the belts and hoses, and flushed the E4OD fliud+filter. So what next?

I'm not doing my own work -- not outdoors at -20C. Any advice is appreciated. Stuff I can do with the $200 or so I have left over from the first round of repairs even better. It'll be spring before I have another whack of money to throw at it.

Chris

 

Replace the thermostat with a 195 degree unit. That should get the heat up, and is what is from the factory. Check the water pump for any leaks, radiator the same. Check the voltage at the battery terminals while it is running, should be bet 13 and 15 volts. Gauge might be wrong. Try to pinpoint the knock. Maybe start looking towards rebuilding the engine, or replace with another one. I have known vehicles that have knocked for thousands of miles with no other problems. Keep an eye on the oil pressure. Maybe install an aftermarket gauge. Don't use the plastic line that comes with them. Buy the 1/8 inch copper line kit to hook up the oil pressure gauge. The plastic lines all eventually break and spring an oil leak. Sounds like you got a pretty good handle on things already. Keep at it.

Robbie

 

Thanks Robbie,

 

I agree with Robbie. He's right on the money. One point I'll make is that it's been my experience that your engine (4.9L) is frequently found to have what some refer to as a "diesel startup", meaning they knock a bit when starting, similar to the way a diesel sounds. I've been told there is an anti-drainback valve you can buy that goes in behind the oil filter to solve this, but they don't come cheap. Also, I've seen 4.9L's with that startup knock go over 300k miles, most of them with that problem.

When is your knock present? Under what engine speeds and driving conditions?

 

The knock is pronounced when it's cold, but still there (just quieter) when it has been running a while.

I wasn't planning on doing anything specifically about it, just continue upgrading or replacing old and questionable parts and hope it goes away. No scarcity of those here. I was thinking it would be best use of money and effort to get everything else up to snuff before having the engine pulled and rebuilt / replaced. We have a 15% sales tax here, so I was hoping to wait on some of the big stuff and drive stateside for that.

So.... thermostat and radiator hoses are next, and check the coolant pump? I sure hope there's no water in there. The jackass who sold it to me put crap windshield washer fluid in it, and it froze solid. Wasn't easy to get out. I already flushed the rad and put coolant in that's good to -45C, and the guy who did it said I should look at replacing the hoses soon. Mind you, he also told me to replace the A/C hoses. I'd be happy to, except there's no A/C on this truck. I went out and bought a code reader yesterday. It's giving a 116 -- coolant temp out or range, and 634 which has something to do with the throttle.

After that.... I don't suppose you have a pic of a PCV valve? I can't find mine. I did find one for $6 at the auto store, but don't know where the old one is.

There are two hoses attached to what looks like an old juice can sitting on the pass side next to the engine. What is that? I'm a PC repair guy. I still don't know where everything is on a vehicle.

I'll post some pics.... it's hard finding stuff that isn't rusty in here.

Chris

 

 

The tin can is a vacuum reservoir. It's job is to store excess manifold vacuum to use when needed. The pcv valve is located just behind the upper intake manifold on top of the valve cover. Hard to see, so feel for it. It's almost directly under where the egr bolts onto the manifold. The thing leaking is the oil pan gasket. They tend to blow out after some time. It is easy enough to replace. It is all rubber, so you can unbolt the pan, and peel the gasket out and install the new one the same way. The fuel pump is inside the gas tank. That's the starter assy.
The "thermometer" is actually the engine coolant temperature sensor. It tells the computer the engine temp. The temp sender for the gauge is on the passenger side of the engine block above the starter. The knock may just be a wrist pin.

Robbie

 

Thanks Rob!

There should be a new gasket in there already, I know I paid for one last Thursday. I'm not doing much of my own work until spring comes if I can avoid it. Working screws and bolts with gloves or mitts on is a good way to drop them and lose them in the snow.

I'm slowly getting it figured out. There's way more parts than a PC.

Chris

 

Sweet mother of......

I just refilled the tank for the first time since I had the work done.

42.85 litres/100km

That's 6.6MPG / 5.5 miles per US gallon

Yikes! Time to check for leaks again.

 

If your mileage is that bad, ie my 81 bronco with 40 inch tires and 4.56 gears and a built 302 gets 12 mpg, you need to spray the intake with carb cleaner. If the engine idles up, or smooths out, you found a leak. The 4.9 is known for its intake gasket leaks. Check every vacuum line and even the "tin can".

Robbie

 

M 4.9 is getting about 3.2 miles per gallon, i just realized. and that's on a properly rebuilt and cleaned carb. HELP!

 

LeClarion, where is your timing set? Should be 10degrees btdc with the vacuum off the distributor. Your mixture screw should be about 2-2 1/2 turns out to start. Fuel filter clean? Smells like it runs rich? Are you sure the carb is right? Accelerator pumps go bad in the Carter one barrel and cause this problem. Automatic, or stick shift? Have you checked for vacuum leaks? Intake gasket where it meets the cylinder head notorious for leaks. Let me know some more info.

Robbie

 

Okay, I know I have vacuum leaks, but how bad I don't know... I have cracked and snapped vacuum lines and at least one that leads to... nothing. It just sits in front of my engine, It's orange, with a 90degree elbow cap on it. The carbeurator is rebuilt properly, and the timing is 9 dbtdc, to compensate for a hi-flow muffler. Mixture screw is 1 and 1/2 turns out from the carb. It's a three-speed auto.

 

LeClarion, can you post a picture? If so, I can tell you what the ghost vacuum lines are supposed tohook up at. I'd bet your intake gasket is the biggest leak, though.

Robbie

 

Huh... I can try. I am replacing the intake/exhaust gaskets, the head gasket, and the valve cover gaskets this paycheck. I put a plug over the phantom vacuum line, though, and the idle got wicked rough and it stopped firing on at least one cylinder, and promptly died. Now, I can't think of a single vacuum line that would do that, so I think that it may be part of a much larger jury rigging.