Epilogue:

700 miles. So far so good. Quiet and smooth. 19mpg best on highway so far - much less in routine use with cold, warmups, 4WD, and snow. No SES lights since repairs completed. With 5W30, oil pressure is 70psi at 2000 when cold - 25psi at 550rpm in drive when completely warmed up. Actually got to use it in the snow! Put my new stereo in with 39GB of Mp3s on a flash drive in the glove box.

Fixing this vehicle took $3000 + all my spare time + seemingly all my thoughts from October through end of the year! With the original purchase price of $5100 + tax late last Summer, I know I have way too much money in a 2001 Blazer - even though it is a VERY nice one. I now actually feel a bit lost without something to do on it! I hope it ends up being a good vehicle.

 

Problems return and the saga continues:

Noticed that oil pressure has been slightly lower when fully warmed up (min 20 PSI at 550rpm in drive) for a week or so. Also noticed that TCC had not been locking up as it had been since repairs completed - thought it strange.

Approx 1500 miles since repairs - March 1 - SES light came on I-80 running 65mph for 20 miles. Drove 15 miles home and checked codes with Torque Pro - was a PO300. Oil pressure was down to 15psi at idle. Cleared and drove to work next day - on the way home set a PO302. Got home and fired up the HP Tuners Software and did a crank relearn which took several tries to get it to complete. Now back to a constant SES light with a PO304 misfire counting up rapidly. Ticking noise is starting to return and can hear bearing noises like before when revving engine 2000-3000 RPM. Looks like the bearings are going out of it again. Apparently the TCC will not hook up with a pending misfire code.

Since engine lasted 1500 miles I am thinking that assembly was not the problem. Because of the previous thrust bearing issue with false misfire codes and things I have read, I am thinking one of several things may have occurred.

1. Transmission pressure problem has taken the thrust bearing out again (have already replaced converter). I have read that restricted cooler lines can cause excessive pressure on the thrust bearing.
2. Electrical ground problem has taken the thrust bearing out again. I have read that bad engine ground can cause starter current to go through the crankshaft.
3. Main bearing bores are not straight. this was specifically supposed to be checked by the machinist. I was told they were all OK without line honing.
4. Engine balance is a problem. Either bad harmonic balancer or flywheel could potentially cause enough balance problems to take out bearings.

The first two I can check with a pressure gauge and a multimeter before the engine comes out again. The 3rd I intend to buy a machinist's straight edge and check myself with the heads/intake on the engine.

The 4th was never checked by the machine shop the first time. This time I'm going to give them the flywheel and balancer along with the crank and rods/pistons to check balance on to see how far out what I had in there was. Then intend to get a different crankshaft, new flywheel, and new balancer - and have all balanced as an assembly.

Anyone know the correct % for the bob weights on the 2001 4.3 V6 with light crankshaft and balance shaft. Machine shop should know but I feel better if they agree with published info and I can't find it. I have read the balance shaft can make a 90° V6 run incredibly smooth but it would not be part of the crankshaft balancing procedure. Anyone have the skinny on that?

Wish me luck. I'm going to need it. This fricking Blazer has become a direct challenge to my abilities and I WILL fix it.

Anyone have any other ideas of what to check while engine is still in the vehicle and running?

 

With the repair of the 4WD issues I have been having and speaking about in other threads, I believe the issue damaging my engine thrust bearing (2x now ) was the encoder motor shorting out and running current back to engine ground through the crankshaft. In late February it was intermittently blowing the ATC fuse for a week or two before the 4WD encoder motor gave up completely. About that time the false P0304 Misfire SES light / lower oil pressure at hot idle / bearing noise returned. Its the only thing that makes sense to me and I think it is quite probable. I have checked the transmission cooler line pressure and it is max of 55psi steady (flash spike of 85psi) with TCC clutch commanded on. This should not be so much to cause excessive forward pressure on the crankshaft thrust bearing. If my machine shop did their job, and I believe they are quite competent, then it's the only thing that makes sense.

So with the 4WD problems fixed and the trans cooler line pressure verified, I'm ready to pull the engine out again and spin a crank into the bottom end without removing the heads or pistons.

Wish me luck. I seem to need it with this vehicle.

Les

 

Anything is possible but i dont really think the theory about the encoder motor shorting through the crank is really logical, if there was any electrical fault to ground it would find its path much easier through the transfer case case, transmission case and the engine block, those are all a much more solid electrical connections than a handful of different sets of splines, gears and clutchpacks that all ride on a film of oil and therefore shouldnt be able to make a good electrical connection. Electricity always takes the path of least resistance, the cases would be the easiest path in my opinion.
If it were me i would reinstall each bearing and torque the caps and measure the bearings for taper, size and out of round, and then do the same to the crank, you need to pinpoint exactly where the noise is coming from. Your original video sounded like any other lifter tick that ive heard in 20 years, probably caused by the torn up bearings releasing metal into the system and jamming the plunger in one. I didnt re-read everything but i dont recall if you replaced the lifters? Also, since intake gaskets were obviously done before you got it then you have no idea how long it was run with coolant in the oil (Or overheated for that matter), the coolant in the oil may be what caused the original bearing damage, once it started it just continued to get worse causing excessive clearance and in turn the low oil pressure. This is just a wild theory...but maybe it had been overheated bad enough to warp a head and blow a headgasket and hydrolocked a cylinder which bent or twisted a rod or the crank? Maybe they slapped a used set of heads on it and dumped it?? Too many what ifs...i know, but im almost positive that your issue is being caused by some dimension thats out of spec or some kind of contamination. It will be interesting to see what you find when you tear it apart this time.
Good luck!! I'll be waiting to hear what you find.

Also, before you tear it down, get an oil sample and send it in for analysis, it will tell you what metals and chemicals are floating around in the oil and if antifreeze is present.
WIX has an oil analysis kit, if you google searcy you can probably find, most auto parts stores should be able to order it too.

 

Sounds logical to me too. I think the encoder searching for ground through the thrust bearing might be a "reach", but, stranger things have happened. If your theory holds true, you should see burn marks on the bearing.


Just an FYI: Years ago, working in a Ford dealer, we used to see Pinto starters find their ground through the clutch cable! Light 'em up cherry red when cranking.

 

Thanks for the comments. This engine got new everything including but not limited to boring 0.030, new pistons, surface heads, new cam and lifters, rods resized, new valves, guides, valve springs, timing gears, torque converter, crank turned including thrust which was tore up the first time. Line bore was checked and was supposed to have been fine. First time the bearings were generally shot, especially the thrust. The clearances I listed in a table earlier in this thread. The Intake had been off but I don't think the bottom end or heads had been off/out. This time I know I'll be paying a lot more attention to the condition of the thrust. Hey, there's a limited number of things that can cause a thrust bearing to go out, and it's not my first rodeo with a crankshaft. This engine was done so very carefully....... I can't even describe it. Pastigauged all bearings their entire width. Did the pry the crank back and forth to line up thrust surfaces and the clearince checked OK. I'm convinced it was something outside of the engine itself causing this thrust bearing failure (and possibly the one before) but of course I have been wrong before..... :-)

 

Thanks Captain, that clutch cable story made my day!

I'm going to give that thrust bearing a 3 times over when we next meet!

I also worked in Ford Dealers in the mid 70's!! Small World! I was one of the lucky people doing the Pinto engine repairs when the rods with oil spurt holes were the fix for the trashed cylinder walls.

The Encoder motor usually ground through the TCCM, but if the motor shells I think it could quite possibly seek ground through the transfer case. I don't know if anyone has noticed all of the corrosion one finds on transfer case bolts? Dissimilar metals ya know...... Isn't that a magnesium case? If there is corrosion between the steel bolt and the magnesium/aluminum, I suppose the inner workings of the transfer case and transmission could become the better path to ground. I checked the t-case for being hot, but at that time the encoder motor had already shelled and stopped blowing fuses. Of course the new motor does not make the transfer case hot. I can't come up with any better theory, and the problems returned all of a sudden and at the same time as the 4WD problem. We will see. In any case, I'm convinced enough to proceed with repaiirs instead of getting rid of the vehicle.

The Pinto clutch cable is hilarious. I saw two hilarious electrical circuits in my former career as a mechanic.

1. 1979 Olds Toronado. Step on the brake, the intermittent wipers would take on swipe across the windshield. Problem was a blown fuse and bad tail-light bulb with element laying across the other, back feeding voltage into the circuit with the blown fuse which happened to feed the intermittent control for the windshield wipers.

2. 1970s Chevy 4WD pickup. Engine would start and run fine until put in drive - then would die just like you turned the key off, Would start right back up and be fine again until you put it in drive. Putting in reverse did not have any effect and would run fine until you put it in drive. Problem was a bad starter solenoid that would tip and short out when vehicle moved forward even a smidgin - since this was one that had the second terminal hooked up to the coil, it grounded out the ignition.

Les

 

Ahh yes, the dreaded piston slap TSB on the 2.3L engine. Job paid 8.9 hours, I remember it well. They never had piston slap after the TSB though. And we can't forget the "Kaboom kit" recall on Pinto gas tanks Couldn't tell you how many of those I did, well into the hundreds I'm sure.

 

Yeah, those were the days! You really had to hustle to try to make a living doing things like that on straight commission at $6/hr. One of the many reasons I went back to the university in 1982. Still worked at a dealer in-between classes and during the summer as an undergrad, but no longer doing heavy work.

 

Yeah, those were the days! You really had to hustle to try to make a living doing things like that on straight commission at $6/hr. One of the many reasons I went back to the university in 1982. Still worked at a dealer in-between classes as an undergrad, but no longer doing heavy dirty work.