91 Suburban - Engine turns overs, Chatters, Won't Fire

[itsallhistory]

I just finished up replacing the engine in my 91 Suburban. The replacement is a boneyard engine (5.7 350) which is the same as the one that came out of it. I got everything hooked back up yesterday - filled the engine with oil and the radiator with coolant - went to turn it on and will crank very slowly but the strange thing is, it sounds like chattering coming from the starter. The thing almost sounds like rapid gunfire (the only sound I could think of to describe it).

I've looked online and some maybe a bad starter or a bad battery. Others have said a bad ignition module or a bad coil. The injectors are getting gas. I haven't checked yet to see if it's getting spark though. It was late last night when I finished up so I didn't pursue it any further.

What do you all suggest as a place to start? Thanks for the help.

 

[chengny]

Do make sure your battery is fully charged and the cable connections are clean and tight (on both ends). A solenoid that is starved for power will often make that particular rat-a-tat sound as it bounces back and forth. Thing is though, that means it isn't driving the pinion into the ring gear so the engine does not normally turn over.

Is it possible that you saw the engine turnover at a time when the starter did manage to engage the ring gear and get a slow crank going?

Or maybe the pinion to ring gear mesh is so poor that the starter is turning the engine over just through friction - and the noise is the gears skipping by each other?

Whatever, it would be wise to make sure the starter is getting full power and also take a few minutes to drop the starter and inspect the teeth (pinion & ring gear).

 

[itsallhistory]

The battery is the one that started the old engine back in April when I pulled it into the garage to start the project. When I tested it with a voltmeter, it showed 10 volts. I put it on a battery charger and got it up to 12.5 volts but it still chattered. Maybe the batter is shot even thought it showed 12.5 volts. We had a hard winter here in OH this year with multiple days below zero. I've had batteries go after a bad winter several times.

Do you think I may have misaligned the starter when I put it back in or perhaps the starter has just gone bad. I'll crawl under it today, check all the connections and pull the starter to visually inspect it. The starter is 3 years old though, maybe time for a new one.

Could any of this result from a ground strap (the one on the back of the block) being loose? I noticed that when I went to reattach it to the firewall after the new engine was in, it didn't seem to tighten down very well. Should I find another place on the firewall to attach it so it's tighter?

Thanks again for the help.

 

[itsallhistory]

It will crank very slowly at times.

 

[HotRodPC]

It dose sound like a low battery or bad connections to the battery. Do you have a good 2/10 amp charger that you can plug it into? I put it on a slow trickle charge for a hours at 2amp. Overnight preferred. If you're working on it and want a quicker charge, do the 10amp charge for a couple hours. Make sure the side post connections are clean and haven't corroded while sitting for a few months.

 

[itsallhistory]

I took off the starter and had it tested. It was in working order, so I took some emery cloth to all the connections. Then I switched out the battery that was in it (a Wal Mart battery) with a high-power Interstate battery. Crossed my fingers, turned the key and it started right up.

Thanks to those who responded!

 

[HotRodPC]

Cool. Glad you got it running. Figured it was a low battery or connections.

 

[89Suburban]

Good job