6.2 turns over slow ... still

[Blzr6.2'83]

I replaced the starter with a normal 6.2 one then with 6.5 gear reduction drive, I replaced the battery cables with 2/0 cables, the alternator is good, and I replaced all wires for ignition and charging on the harness. It still turns over too slow to start. I have an injection pump and injectrs from July 2005, a new high flow oil pump I put in Nov 2005, and a new water pump and powersteering pump put in this summer. I have talked to people and they said it should be the starter, the grounds for the batteries, or the engine is too hard to crank over. The engine has about 170000 miles on it. The problem came slowly and finally got to the point where it would not start at all. I need help and must get it running before school starts Jan 17. Any ideas?
Thanks,
Kyle

[john8662]

How are the batteries?

Take BOTH of the batteries off the blazer and have them tested at your local auto parts store. Come back after they're charged and tested for the verdict.

If you have a weak battery if will cause this. But, if you've gone through all the trouble of changing your cabling and ends then you're probably sure you've got some great batteries.

In my opinion, the stock cables work plenty well if they:

A. Get the terminal bolts upgraded "improved side terminals"
B. have good clean (bare copper connections) at the batteries.

How are your ground connections to the engine block from the batteries? Remember, the battery leads connect at the water crossover on both sides. This is a source for corrosion, from the presence of current and the seepage of coolant from leaking gaskets at the crossover.

I'm suggesting pulling the studs that hold the crossover (just the two that have battery leads going to them, then clean the threads of the bolts with a wire brush, then re-install them. Then follow up by cleaning the ends of the battery cables going to the studs and make sure that the "star" washers are present that go on top of the electrical connection before adding the nut.

If this doesn't help...

Take and get your favorite 1/2 drive ratchet or 1/2" break over bar and appropriate socket that fits the harmonic balancer bolt and attempt to rotate the engine. You should be able to rotate the engine by hand (clock wise only preferred).

How easily can you rotate the engine? I'm a little worried due to the low oil pressure problems you've had in the past that a bearing that was worn could have "stacked" and cause the engine to be almost locked up. I hope this isn't the case.

[Blzr6.2'83]

I replaced the batteries with two optimas with 850cca and it is still the same. I will move one ground to a intake manifold bolt and the passanger side to a starter bolt. If that doesn't help I will see how hard it is to turn over by hand and tell you tommorrow or friday. How hard should it be to turn over with no glow plugs? I will try that also. Looks like I might have to pull the oil pan again, but by now it is pretty easy since it will be the fourth or fifth time.
Thanks again,
Kyle

[twaddle]

Are you getting any smoke at the ex pipe?
Is the inj pump shut of solenoid getting voltage and Current?
Are your glow plugs actually getting enough current?
I have a situation with my 6.5 Suburban just now that my glow plugs seem to get voltage but they are not getting enough current to start the engine. If I short out the heavy connectors at the GP relay the engine fires up ok.

Good luck

Jim Twaddle
Biggar, Scotland

[Blzr6.2'83]

Yeah there is smoke coming from the exhaust and it is trying to start, but just isn't spinning fast enough. It will start with starting fluid and the glowplugs off though, and seems to run fine after it starts. What are stacked bearings?

[Blzr6.2'83]

Yeah there is smoke coming from the exhaust and it is trying to start, but just isn't spinning fast enough. It will start with starting fluid and the glowplugs off though, and seems to run fine after it starts. What are stacked bearings?
Can the main bearing be replaced with the engine in place and the crank still in? I just need this engine to last another 6 months until I can finish my rebuild on my red block.

[john8662]

Since you've mentioned that you can get the engine started with a starting aide, then the problem isn't likely to be a stacked bearing.

Stacked bearings are when either a rod or main bearing (mostly happens on rod bearings) becomes so thin and the clearance excessive that it will roll and stack on top of the other thin piece of bearing. This will cause the engine to still be able to turn, but really hard. You will get a knock and next to no oil pressure.

Perhaps you've got a grounding problem, or the starters you've got are not up to the task.

Are the starters new?

Also, speaking of grounding, take and clean the mounting surface on the block where the starter mates. I do this with a razor blade to expose the raw metal on the block (it has paint there). But, you really should be getting a ground at the bolts themselves, something I've tried and helped once...

[CleviteKid]

John mentioned starter bolts, so let me make my occasional recommendation:

Every time you change oil, put a torque wrench on the starter bolts and make sure they are torqued to 40 ft-lbs. And make sure the front bracket is in place between the starter and the engine block. This will almost completely eliminate breaking the starter bolts and giving you an unpleasant repair job.

Dr. Lee :cool:

[Blzr6.2'83]

I ran a ground cable to the intake manifold and the other to a bolt on the starter. It turns over faster and might beable to start now if I replace some of the bad glowplugs, but it still seems slow. I can turn it over by hand with the fly wheel fairly easily, but have no idea how hard it should be. Does any one know how to test if the engine is too hard to turn over?
Thanks,
Kyle

[john8662]

I suspect that you're good to go on the turning of the engine by hand. If you can turn the engine over by hand using the flexplate, then you don't have the condition explained earlier. When a stacked bearing condition happens, you won't be able to turn the engine from underneath easily at all, and the starter will just baraly turn the engine over, will feel like a completly shot starter, or one that just has enough juice to engage but not turn the engine over.

Which starter do you have mounted to the engine now a gear reduction starter (6.5/6.2L) or the direct drive starter (6.2L OE)?

I agree with Dr. Lee on the above statements regarding starter torque, except the torque rating. I only use 35 ft. lbs. This is a caution I've used because of a few instances where I could start to "feel" the threads pull in the block, but it was most likely the aluminum case of the starter compressing or bolts strecthing etc. I'm probably overly cautious, though, and the torque that I'm using has never gotten loose or backed off.

But, the true genuine advice given above for ANY 6.2 and 6.5 is to make sure that you have the front support bracket installed, it's manditory. It has to be firmly attached to the block and the starter.

I'm drawing a blank on the cranking problem, how well charged are the batteries? I suggest installing your BEST starter, and charging the batteries on the low amperage setting with a crackle box charger overnight (most have a regulator that switches on and off throughout the charge cycle).

Ditto on getting the glows working completly, check them all with a test light to avoid un-necessary replacement.

[Blzr6.2'83]

I have the gear reduction one in now. What is the bracket? I am not sure that I have one.

[john8662]

There is an almost "L" shaped bracket that connects to the rear of the starter (opposite drive end). You'll notice that one of the bolts on the starter's case (direct drive starter) will have stud to attach a nut to. The gear reduction starter has an ear that has a stud sticking out of it in which to attach the bracket to.

The bracket attaches to the starter, and then up to a boss that's on the side of the block. This holds the back of the starter up and keeps the starter from flexing while it's got the load on it. One other possible ADVANTAGE to the bracket (besides saving you from breaking starter bolts) is that it COULD provide another ground source for the starter to the block.

Part Numbers (yes, different bracket for different starter)

Direct Drive Starter Bracket: 14028931
Gear Reduction Starter Bracket: 23502557