Hey all,
so i bought myself a beater 2000 Blazer 4.3L. the engine was running rough and it was because the intake gasket needed a replacement ( i was told )
so i replaced the gasket and plugs and sure enough, there was coolant in the oil. i changed all fluids etc. than spend another day and a half troubleshooting the distributor and adjusting the timing so it could start.

the egine runs rough but it starts up everytime, i even took it for a little spin around the block ( after oil change ). the thing is that it still runs rough and not to my liking. scanned for codes and saw P0300 multiple misifires.

i have tried to adjust the timing again and again but with no resolve. i saw on forum that if you put a piece of paper to the exhaust while its idling and if sucks it up that it means that you have a probem with rocker or a stuck valve.

i am planning on onpening up the heads, probably good idea to change gaskets while at it. hopefully nothing is broken or bent (rods).

quick question. would rislone treatment or seafoam treatment be a good start?
i have to change the oil regardles so might aswell try it..

 

Have you thought about verifying fuel and ignition before you tear into the heads? There is more than enough information on this forum to save you some pain.

 

Thought about it, i had the gaskets ready to go so i decided to open up the heads but couldnt find anything. after reinstall i the truck wont start. im thinking that i might have over tightened the rockers (thats what everyone says) but the bolts that hold the rockers have a stop on them.. so its not like you can over thigthen them.

as of know the truck is sitting i havent had time to tare it apart again to see what i did wrong ( it was running before atleast**) i will be doing a compression test 1st to see if the valves are holding pressure if they are not i will have to open up the covers.
i just have to wait for a dry day ( live in raincity Vancouver**) planing on spending whole day this saturday.

if i do, however get the truck running and it still idles rough with 0300 than i wll pursue fueling injection system ( i know i should have started there 1st, but i did buy the truck with coolant in the oil lol..)

 

At least do your basics before you just assume it must be something in the heads. I'm just trying to say maybe your putting your cart before the horse. Like I said before, There is plenty of info here to get a good solid result, might save you some busted knuckles and head scratching.

 

Ignition timing is determined by the crank sensor and the PCM. Has nothing to do with the distributor. If you turn the distributor housing, then all you do is change the rotor position relative to the cap and this in itself can cause a P0300 misfire. The setting for the distributor housing (this is called Cam Sensor Retard or CMP retard) is locked in place by the factory distributor hold down and is non-adjustable. If you modify the hold down or replace it with a old style distributor clamp so it can be turned, then it is absolutely imperative that you check and adjust the CMP retard using a capable scan tool. Otherwise the (correctly timed) spark may jump to the wrong terminal inside the cap (or to ground) and cause a misfire. The setting for CMP retard is 0° ± 2°. Typical problems with the distributor itself causing misfires tends to center around bad caps/rotors, worn distributor gears, and CMP retard setting not being correct. Also high on the list for misfires are spark plugs, wires, vacuum leaks, and fuel system problems (including fuel pumps, filters, injectors, and pressure regulator). Mechanical problems can also cause misfires, but that is not quite so common. However, a man recently and successfully went through P0300 misfire diagnosis and 2 bad cylinders were found with a leak down tester. The operation of each system needs to be verified during P030x misfire diagnosis, which happens to be one of the most difficult to chase. It has to be done logically and fully to mean anything.

So it seems you are definitely losing ground with what you have been doing to your vehicle. Now you need to figure out what you did to cause the no start and fix that before you can go back to diagnosing the misfire.

Why won't it start now? Possibly you now have the distibutor dropped in wrong - maybe 180 out. You seem to have a lot of trouble getting the distributor in right, but it could be anything. With the engine on TDC#1 (both valves closed or right after you feel compression stroke in spark plug hole - one mark on the balancer points almost straight down and the second mark to the indentation/mark on the timing cover), the distributor should be dropped in so the rotor points as close to the "6" stamped into the top of the distributor housing as possible. Valves are non-adjustable - just torque the nuts down against their stops.

IMHO 2nd gen Blazers are way too complex and full of electronics/options to make good "beaters". If you intend to try treat it as a beater, why should I help you on a Blazer enthusiast's site? So are you commited to doing the work required to diagnose and fix your vehicle, along with obtaining the required tools? if so you may need any or all of the following: fuel pressure gauge and fittings per the sticky at the top of this forum (gauge can be borrowed with deposit from local parts store), an Android phone or tablet with Car Gauge Pro (Google Play Store) or Car Diagnostic Pro (Amazon), the BAFX bluetooth OBD2 adapter (Amazon), a digital multimeter, and a compression gauge or preferably air compressor with leak down tester. You can plan a minimum of AC Delco Cap/Rotor and Spark Plugs for parts.

Telecaster recently went through the diagnostic process successfully and fixed his P0300 after changing his intake gaskets. You might want to read his thread to see what you can be in for once you get your vehicle started.

You also might want to look at the thread where reevesjo successfully diagnosed the two bad cylinders causing a P0300 misfire at idle.

Let me know.

 

Hey Lysmayer, thanks for all the info truly i appreciate it!
i am fully committed and i intend to bring this blazer back to life haha, since i live in vancouver area and i like to go up in the mountains snowboard/hike.. sometimes my poor little cobalt SS/TC have hard time making up the hill with the FWD hehe...

i have a pretty good idea how to adjust the distributor at this point since i have done it so many times. i know it cant be timing this time as i did not touch the distributor before i parked it to do the valve cover gaskets..(the truck ran and started up everytime before i parked it)

as to the tools, i got everything i need OBD2 scanner multimeter.. tablet is already setup to read the CMP and whole bunch of other good things. i got myslef fuel pressure gauge and compression tester ( that is what i intend to start with tomorrow).
the truck got new plugs and wires in so far.. i was hesitant to change the cap/rotor at first but i will see if i can pick one up aswell before i start.

as you said, i first will have to make it run again than im back to square 1 with the p0300. i have read throuh some of the threads that you have assisted with the 0300 and i feel like ive got a pretty good shot hehe. i work as a instrument tech so troubleshooting is my living haha.. another day in the paradise.. i just wish the weather was a little better

i will deffinately keep everyone posted here are few pics (because we all know thats what everyone always looks for in a thread =P)

 

Great!!

Awful lot of water whipped up with oil in your lifter galley in that first photo. Hope that you got that flushed out somehow? Please tell me about it.

Hate to be the bearer of bad news, but that milky antifreeze/oil mix has probably has damaged your engine bearings beyond repair. Nevertheless, we will go on - just keep that in mind. It's worth getting it running to see.

Or is that milky stuff some sort of engine degreaser?

So you never had the heads off? From previous post I thought that you had taken them off. In reality you meant the valve covers and rocker arms, right?






Please begin by checking the following three things in this order. Don't assume anything from any previous testing or work - do it all from scratch:

• Rotor pointing to #6 when engine is on TDC #1
• Spark at coil wire
• Fuel system pressure and leakdown tests (all 4) per sticky at top of 2nd gen forum.

Then please report your findings. If all is good, then we will continue with other things.

Get an AC/Delco cap and rotor if you are buying new. they are worth it on the Blazers.

 

Yeah i have flushed it 3 oil changes so far and cleaned up as much as i could when i had it opened. never had the heads off, you are correct i only took the intake gasket and valve covers off so far.


i did a little reading and as i was puzzled to why there were 2 markings on the balancer.

how close do i have to be to align the notch with the pointer? (#1 to #2 on the pic)

i will try to align the timing again this time i will check if both notches align as per pic below, all the times before i only check if the top one was aligned..

 

The top mark should align exactly with the notch in the timing cover. Only 1 and 2 are important. but you need to make sure it is #1 mark you are using Not sure what the purpose of the second mark is - something for the factory or maybe the same balancer is used on a different engine. Lining rotor up with stamped "6" cast in the distributor housng (not #6 terminal) should be close enough for engine to run. Then we will use CMP Retard value to get the rotor position exactly on target but first the engine has to run.

 

roger, ill have the ducks lined up for tomorrow. expect update later on tomorrow