Knocking air compressor, could use some advice

[767Jockey]

I have a 5HP 60 gal Sanborn Magna Force compressor. It was given to me, and when I hooked it up, it has a loud knocking coming from the pump head. It works just fine, goes right up to pressure, all functions are normal.

The question is, do I rebuild this pump, or do I buy a new one?

If I rebuild, where do I get the parts? Are there directions available?

If I buy new, do I buy the same pump again? Where do I get it? If I buy another pump, what do I buy? I'd like it to be as close to bolt on as I can get.

I'll attach photos here. Can anyone identify this pump visually? All I know is that it is a two stage pump.

Thanks for any and all info and advice. It works really well, but it's very loud and annoying when it's running.

 

[Cyberbear]

Based on your pictures, you have a well used unit and the pump needs to be replaced as the most cost effective way to go. If the motor is still operational w/o problems, look online to find a suitable replacement pump that matches what you have. Once repaired the unit should last a good while if you do the proper fluid level maintenance. You may start by looking at Harbor Freight and go up from there until you find what you are searching for w/i your budget.

 

[redmondjp]

That looks to be a Bel-Aire/IMC B4900 pump (Italian-made) for which I think you can still get parts. Here is an exploded diagram of the pump, which has a slight difference from yours, Item 21 which is an aftercooler which yours doesn't have - you have the smaller discharge line coming straight out of the head instead.

http://www.i90enter.com/b4900-pump-parts/

 

[CompressorPros.com]

Definitely a B4900/T29S pump without the aftercooler. The knocking could be bad rod inserts or wrist pin. There is an overhaul kit for a couple hundred bucks, but until you get into it, there's really no telling what is knocking. A new pump (with aftercooler) would be $649

 

[gayler]

Is there any oil in it? To my poor eyes it looks like no oil.

 

[maxpower_hd]

I have had some good results with Master Tool Repair. Here is a link to the Sanborn compressor section. http://www.mastertoolrepair.com/col...-coleman-sanborn-pumps-parts-c-271_35_81.html

There is a pump section but there are only a few high end ones in that section. For yours you will need to go to the parts section and one of the parts is often a new pump. They have some decent descriptions that help determine which one you will need. The ones I looked at quickly that might match up to yours were more in the $300 range.

Good luck.

 

[Davefr]

Is there any oil in it? To my poor eyes it looks like no oil.

Oil level needs to be checked in the upright position.

Thanks for any and all info and advice. It works really well, but it's very loud and annoying when it's running.

That's inherently a loud running compressor. My advice is to run to fail which may be many years. Other then HF's Chinese pumps, there really is no other cost effective pump replacement IMHO.

A replacement B4900 pump will cost way more then the compressor is worth.

 

[Rag Roc]

Have you checked the belt tension? My used compressor was making a banging noise, then squealing. A new properly adjusted belt solved the problem. Felt pretty stupid.

 

[767Jockey]

Belts are tight, oil has been replaced and is full to spec. I have an old mechanics stethoscope, it's very definitely coming from the crankcase of the pump. Does the rebuild kit come with new rod bearings? I can definitely tear it down and rebuild quickly if I have some sort of directions to at least help guide me. I see where to get the rebuild kit (thanks, CompressorPros.com), I just worry that I know how to do the job correctly once I get the kit. I rebuild engines regularly so I am guessing I'll be able to figure it out, but directions would certainly be helpful if I get stuck on a proprietary component.

 

[CompressorPros.com]

I'm checking to see if I can get the full contents of the kit...will hopefully post shortly. If you can rebuild an engine, you should be good to go.

 

[CompressorPros.com]

It looks like they changed the kit and I am waiting to hear back if there is an alternate part number. Sorry for the delay.

 

[maxpower_hd]

I rebuilt one a while back and it was really pretty easy. Just make sure you pay attention to how you take everything apart and lay everything out in a way that you know exactly how it goes back.

 

[CompressorPros.com]

Just got confirmation that the kit, 6229017300 contains gaskets, rings and connecting rod inserts.

 

[redmondjp]

Just got confirmation that the kit, 6229017300 contains gaskets, rings and connecting rod inserts.

And you are lucky that your pump has connecting rod inserts - the lowest-end compressors don't, just like most lawnmower engines.

 

[767Jockey]

Just got confirmation that the kit, 6229017300 contains gaskets, rings and connecting rod inserts.

OK, I guess the best thing to do is to order from your website? I'm hoping that the rod inserts quiet the knocking and that it's not a wristpin or a wiped out crank. I'll keep my fingers crossed.

 

[sberry]

Tear it apart before you order parts.

 

[sweetk30]

Tear it apart before you order parts.

x2 on this idea.

and I have almost the same problem with mine but a blackmax unit .

she takes for ever to even get close to the shut down pressure and last night after 5-6 min I gave up and turned it off . started at 50 psi and never got past 110 psi . no load on the system for air use . the ir-temp gun showed just under 300* head temp

I think she has givin up the ghost . . . . going to look at a good used ir t30 style unit Saturday for 250 bucks . even if it needs a fresh up I will be money ahead on this unit over the factory unit. and my buddy going with me use to be a engineer at a ir air tool / comp plant so he knows them

 

[btdobie]

Not near you unfortunately, but they can be found cheap if you're patient. http://mankato.craigslist.org/tls/5679772577.html

 

[Davefr]

Tear it apart before you order parts.

^^X3. You could go thru all the expense and trouble of rebuilding the pump just to find that it's still very "loud and annoying".

Compressors with this pump run fast and loud. Read for yourself.

http://www.harborfreight.com/5-hp-60-gallon-165-psi-two-stage-air-compressor-93274.html

 

[sberry]

Or order parts and then find out something else is wrong or you need to add to the order. I know people stop tear down the first thing they find, start to order, parts come in, then tear down, big surprise....?

 

[CompressorPros.com]

These do run around 1350 RPM depending on the motor RPM and pulley size, however, they have balanced pistons and crankshaft, so they run smoothly compared to similar machines. If it is knocking, it would be significantly louder, plus a sign of potential failure.

 

[redmondjp]

These do run around 1350 RPM depending on the motor RPM and pulley size, however, they have balanced pistons and crankshaft, so they run smoothly compared to similar machines. If it is knocking, it would be significantly louder, plus a sign of potential failure.

And the best way to test for knocking is starting up the pump with an empty tank - if there is any slop in the rod bearings or wrist pin, you will here it the most from zero to 15-20 psi.

 

[767Jockey]

All sounds good, I'll tear it down and go from there. One last question. I just noticed that the flywheel has sort of cast in fan type blades and one is missing. I just checked and it runs absolutely true, no wobble at all. Is there going to be any balance type issues from this? It doesn't seem to spin fast enough for balance to be a huge issue.

Ideas?

 

[redmondjp]

All sounds good, I'll tear it down and go from there. One last question. I just noticed that the flywheel has sort of cast in fan type blades and one is missing. I just checked and it runs absolutely true, no wobble at all. Is there going to be any balance type issues from this? It doesn't seem to spin fast enough for balance to be a huge issue.

Ideas?

You could put the flywheel on a cone-type lawn mower blade balancer and see how far off it is. You could drill out some material on the opposite side of the flywheel, across from the missing blade. But personally, I wouldn't worry much about it.

 

[pancho400cid]

Maybe it busted when the unit fell over? Hopefully a bent crank is not the issue you are fighting.

 

[maxpower_hd]

Missing as in it broke off? In the pic you posted it didn't appear there was any damage at all to the guard or the flywheel. Those fins are also supposed to help cool the head but I doubt it would make a world of difference with one missing unless you were running it 24/7 or something.

I would question whether or not the damaged flywheel might have something to do with the knocking noise though. You will likely learn more as you tear it down.

 

[motoguy]

Resurrecting a dead thread. I also have a B4900 that just died and needs rebuilt. It's on a Harbor Freight 60gal compressor. Looks like a rebuild kit is going to cost me ~$250. New pump would be about $550. Whole new compressor is $800.

I've purchased the dual cylinder, 5hp $170 HF pump to use in the interim. It's only a single stage, but seems to have good reviews from those I've asked before purchasing. Should I rebuild the B4900 (add $30 for the air filter kit to make it a T29S) for $250, buy a whole new pump for $550, or just wait to see if I have problems with the HF pump first?

I know myself, and if I have a good working pump lying around, I'm going to start looking for a 5hp motor and another tank...

 

[redmondjp]

Resurrecting a dead thread. I also have a B4900 that just died and needs rebuilt. It's on a Harbor Freight 60gal compressor. Looks like a rebuild kit is going to cost me ~$250. New pump would be about $550. Whole new compressor is $800.

I've purchased the dual cylinder, 5hp $170 HF pump to use in the interim. It's only a single stage, but seems to have good reviews from those I've asked before purchasing. Should I rebuild the B4900 (add $30 for the air filter kit to make it a T29S) for $250, buy a whole new pump for $550, or just wait to see if I have problems with the HF pump first?

I know myself, and if I have a good working pump lying around, I'm going to start looking for a 5hp motor and another tank...

What died on the B4900? Knocking sounds and/or bad bearings? Or does it just need the reed valves replaced? I coworker of mine just did the rebuild kit on one of those and it turned out well.

 

[kbs2244]

If you know how to repair an engine then you know how to repair an air pump.
An engine is just a pump with a carb and sparkplug added.

Open it up, see what is broke and order what you need.