Distributor timing problem

chevrolet
blazer

#1

I replaced the lower intake manifold gasket on my 1998 blazer.

Now i`m trying to get the distributor back in the right spot.

In theory it`s suppose to be easy on this 4.3L engine.

I turned the harmonic balancer pulley with a socket and breaker bar to the point where the 2 timing marks are lined up.
I installed the distributor so that the rotor lines up with the arrow on the distributor body, which is the number 1 cylinder.

When i try to start it, it just cranks but doesn`t fire up.

Then i removed the distributor and rotated the rotor so that it is 180 degrees from the arrow and the engine starts but it revs up to 3,000 RPMs and stays there for a few seconds then drops down to 500 rpm and stalls. when it drops below 1,000 RPMs i can hear popping coming from the engine so im pretty sure that the rotor isnt in the right position.

so, what i am doing wrong i didn`t crank or turn the engine after i removed the distributor to replace the gasket.
before i removed the distributor the first time, to do the gasket,i turned the harmonic balancer pulley so that the timing marks were lined up and the rotor was pointed to the arrow on the distributor body.

i`ve spent 8 hours taking the distributor out, turning the rotor a little , put the distributor back in and try to start it.


#2

Sounds like you had it at least close to correct at that point.
Revving high then stalling could be a massive vacuum leak.
Make sure you put all the hoses back in the right place.


#3

ill check all the hoses again tomorrow, i hope the new gasket isnt leaking.

ill check the gasket first, ill start it and have my neighbor spray starter fluid around the gasket and see if it sucks it in.


#4

Nowhere in the post did you mention the use of a timing light. You DID use a timing light, right? You can’t just set these things statically and expect it to be dead-on. Retarded timing will drop the idle speed. And of course you disconnected the single wire connector that allows the truck to be timed, right?


#5

Just curious.
By 1998 were there still vehicles where the distributor timing could be adjusted? I thought OBDII put an end to that in 1996.


#6

+1.

In addition, you should recognize that the spark plug doesn’t fire every time the piston reaches (approaches) TDC, it fires every OTHER time. When replacing a distributor, or when unsure, the best bet is to remove the valvecover and watch the valves. As the piston reaches TDC (which you can determine by putting a wooden rod in the spark plug hole) after the intake valve has opened and closed (that’ll happen as the piston goes down the cylinder), that’s where you’ll want to align the marks on the crankshaft harmonic damper and then align the distributor rotor. From there you’ll definitely need a timing light to get it properly timed, but at least you’ll be in the proper neighborhood.


#7

You don’t use a timing light on this 1998 Blazer. I know, because we still have a few in our fleet

Timing is non-adjustable. The underhood sticker even says so, and the the distributor can’t be rotated, once it’s dropped in place. It’s not slotted.

If your timing is too far off, you’ll get a check engine light, and the appropriate code, because “cam synch” is way out of spec

The factory service information doesn’t even show you how to check timing with the light, in any case

As for OBD2 cars and non-adjustable distributors . . . that is a blanket statement, which is incorrect. Generally speaking, it’s true, but there are exceptions. For example, my former 1997 Protege had a slotted distributor, and the factory service information clearly said to check the timing with the light. After doing my timing belt, I had to adjust it very slightly, so that the ignition timing was perfect.

And several of the OBD2 GM vehicles in our fleet have slotted distributors. Those are V8 models, though. You check cam synch at a certain engine speed . . . could be 1000rpm, it’s certainly not at idle, I’ll tell you that . . . and adjust the distributor until you’re within specs. That was for the 5.7 and 7.4, and they were both built long after 1996


#8

If the OP rotated the distributor 180 degrees from the correct location (marking on the distributor) they didn’t have the crankshaft in the correct location. They needed to rotate the crankshaft another 360 degrees to get the #1 cylinder on compression, then install the distributor correctly.


#9

I got it,
I put the distributor in and turned the crankshaft with a socket and breaker bar until the rotor lined up perfectly with the arrow on the distributor housing.That got the oil pump shaft,the rotor and the arrow lined up.
then i removed the distributor and turned the crankshaft until the 2 timing marks on the harmonic balancer lined up.
then i put the distributor back in and everything lined up (the oil pump shaft, rotor and the arrow) and it dropped right into place.
The problem was getting oil pump shaft and the distributor to line up, without throwing off the rotor and arrow on the distributor housing.

You need to get the rotor and the arrow lined up precisely.


#10

Thanks for posting how you got it fixed. Besides the oil pump shaft alignment issue, when installing a distributor usually you got to get the crankshaft and camshaft in the tdc-compression position first. Rather than the tdc-exhaust stroke position. That means air will be pushed out of the no 1 spark plug hole pretty vigorously as that position is approached. Also good idea to verify that the distributor rotor is pointing at the number one spark plug wire connection on the dist cap.

Some twisting is often needed during the process to match up the spiral gears involved. It seems like if the distributor wasn’t mating up with the oil pump shaft properly, it wouldn’t have fully seated level on the surface where it normally sits. Did you notice that problem happening?