Ingersoll Rand P185 Tow Behind Compressor Parts, Manuals, Information

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There are probably tens of thousands of Ingersoll Rand P185 tow behind air compressors in use and for sale around the world. This article will provide you with all the relevant information on Ingersoll Rand P185 town behind compressors.

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Ingersoll Rand P185 Tow Behind Compressor

I have not been able to get any specific information on this venerable compressor from IR, except that it’s a portable compressor – being that it’s a towed air compressor – and that it’s designed to provide 185 CFM of airflow when running optimally.

It appears as though Ingersoll Rand is no longer selling portable construction compressors, preferring to manufacture and sell construction equipment like jackhammers and what not as well as industrial air compressors.

We understand that the portable construction compressor business was sold to Doosan Portable Power. If you have information confirming this, we would appreciate an update via the comment form below.

Ingersoll Rand P185 Tow Behind Compressor
Ingersoll Rand P185 Tow Behind Compressor

In the absence of troubleshooting information for the P185 family of Ingersoll Rand compressors, I am providing a forum here for users to post questions and respond if they can.

Have a look, add your question here about the Ingersoll Rand P185 tow behind air compressor, and if you can help another user with some knowledge or advice, please add a comment.

All IR P185 compressor users, and me, say thanks,

Ingersoll Rand 185 and P-185 Tow Behind Air Compressor Manuals

Just in – Ingersoll Rand 185 manual.

And a big thank you to Doug from S.D.Ca for this P-185 parts manual.

Feel free to download either to your computer.

Have an issue with your Ingersoll Rand (IR) P185 tow behind air compressor?

If you scan the existing postings below, you may find an answer already there. If not, scroll to the bottom of the page and add your question.

Can you answer one? Please leave your advice as a comment on any of the existing postings about the IR P-185 air compressor.

Thanks from all of us.

Ingersoll Rand Tow Behind Portable Air Compressor Troubleshooting

Existing Ingersoll Rand P185 tow behind compressor pages:

If you have any questions regarding Ingersoll Rand tow behind compressors, please leave a comment below, with a photo if applicable, so that someone can help you!

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I recently purchased what I believe is a 101 CFM 1987 Ingersoll Rand tow behind to blow out irrigation systems. The machine is in great condition and the motor runs solid however I have low air supply volume at about 40psi. I’ve changed out the air regulator and I still have the same problem. If I hold in the test air button and dial up the regulator the machine will build up air really fast and if I can dial up or down the regulator I can get the psi to stay high enough before the pressure relief valve activates… Read more »

Can someone tell me why the coupler on my 185 constantly breaks. The machine has 600 hrs and I have literally changed the coupler 10-12 times over the last 10 years. I just changed it last week and it broke in 2 days. What is going on. What is everyone missing when they change this thing or low oil etc. any ideas ??

I have a 1999 P185WJD that runs great and blows lots of air, except it has developed a high pitched noise at the air end. Using a stethescope, I’ve located the source near the unloader valve housing. I took apart the unloader and found that the piston was badly rusted on top due to water accumulation over the years. Cleaned everything up, reassembled it and guess what, the noise was still there. I’m now thinking it is either the engine/air end coupling or a bearing. The noise is loudest in the unloaded state and seems to disappear when in the… Read more »

I’d guess the unloader isn’t closing right. Probably a side effect of the rust.
You might try to block or reduce the airflow with a screwdriver handle or something to see if the noise changes. Potentially a lot of vacuum there, so be careful.

I’ll give that a try. I’ve never had one of these airends apart, but it looks like the two screws are gear driven because they are offset from the engine crankshaft centerline. I am trying to obtain a rebuild manual but IR/Doosan is very secretive about them. I did run across a P175/P185 Airend Rebuild service manual on Ebay in the UK, but it had sold. I’m planning on pulling out the air separator and the airend to inspect for excessive wear, especially at the coupling.

Yes, they are gear driven for efficiency – the screws very nearly touch. So yes, if there’s enough slop they could touch. You do have oil in it, right? There might be a filter in the scavenge line that could be clogged, possibly starving it for oil at the intake end.

I pulled the scavenge line and cleaned the check valve. No change in the noise. Yesterday I dumped the oil from the oil separator. It looked ok, slightly dirty but not bad. The manual says that the compressor oil capacity is 3 gallons and that is about what I collected. I’ll remove the oil filter and cut it open to check for metal particles next. Thanks for your help, much appreciated.

I ran the compressor without the air cleaner hose and in the unloaded state the valve is not seating 100%. It’s hard to tell if that’s the noise source though. In the loaded state, the valve opens properly when the service vale is opened. Could a weak spring be the problem?

Hi. I recently purchased a clean IR 2008 p185, guy said is well taken care of he had done seals on air end a couple years ago so should not have problems… its running and blows air but noticed is not as strong as other 185s we have at work(ie:atlas copco) the engine revs up when i open valve and psi is at around 130 and holding… seems fine…. its just that air wont throw my hand back like the other compressors when i put it in front of open valve…. i was expecting more force. what can be holding… Read more »

Could be a few things, but normally those run around 100psi, so the regulator is maladjusted.
That might have damaged the separator, so that’d probably be the next thing to check.

1)So what do i change, the filter in the separator tank? What else in the separator tank would i have to look at?….. 2) About the regulator, it works but theres a bleeder (orifice, muffler) T’d between it and the plastic line goin to air end, its always bleeding air. Is that how this regulator works? By bleeding air out the orifice muffler? Comparing to other p185 only have found mine to be this way. 3) Also, noticed the air end assembly / case seems way smaller than the other ones but i guess its just my year model dont… Read more »

Please download the p185 manual, and read the operation and troubleshooting sections for a better overall understanding of these things. Also, pix of the areas of concern would be helpful. You’ll likely find there are differences in how things look in the manual and what you have, but they’ll be in the same general area. On to your questions, inline… 1)So what do i change, the filter in the separator tank? What else in the separator tank would i have to look at?….. Well, you check it. It could be plugged up or collapsed. If it’s not obviously bad, you… Read more »

Hi, sorry, i had to go out of town for work but im back.

Cool. Let us know what you find out, please.

You might have a faulty minimum pressure valve preventing full flow of air from the separator tank. Your inlet valve may also not be opening fully.

Why are the pictures not loading ive been trying and then i have to wait days for a msg to be approved to check if it went through. I attached pics to my previous msg and i see nothing…. but just the text

Where is that minimum pressure valve? Inlet valve does what i stated in number 4 on previous comments, it opens like around 3/4 inch then wants to close back up like 1/4 or less when i fully open service valve i figured since theres no back pressure i guess i dont know. I still need to check what Doug suggested in separator tank. I have been uploading pics but they dont go through. I really appreciate you guys taking your time to help out. Im really grateful. Also, i honestly think there would be more follow ups and responses of… Read more »


I have a p 185 , it releases Hyd oil from the brass vent fittings at the adjustable regulator, any one know the problem ?

Pic please.

Just purchased a P185 WD looking for operating manual I can only find P185 WJD can you tell what is the difference.

I think the D is for Deutz and JD is John Deer engine.
The rest is the same except for various control panels, so if you can post some pix, I may have a manual for it.

Does anyone know of JD motors for this air compressor. Mine is bad, and not overhaulable. Also are there any used parts suppliers for this air compressor. Since there are so many, suprised that there isn’t a secondary market of parts.

Is there a way to test air end of P 185 that has a bad diesel motor?

I don’t think so, other than putting it on a good motor.
Are you thinking of buying it just for the air end?

No, deciding if new or different motor is worth buying. Current one isn’t worth overhaul.

Ah. Unless it pumped sand or something for a spell, about the only thing to wear is bearings, so if you can turn it by hand and it’s smooth going, it’s probably OK.

Hi, I have a 94’ ingersoll-rand 185 pull behind unit. Worked fine until yesterday. For some reason when you turn it on it runs really high, same high (speed) when you push the service air button before it lowers its idle to normal. It runs high and nothing happens, you push the service air button and nothing happens not is there trapped pressure anywhere, as if the air compressor is not even connected to the engine. It just turns on and stays idling high. Need some help….

“as if the air compressor is not even connected to the engine.”
Maybe that’s it. Have you checked the coupler?
If not the coupler, what else have you checked?

Well i dont really know where to start, it ran just fine a few days prior. It never made any strange noises nor is it overheating. Once we turned it on it went straight to the high idle and it just stays running like that.

Can you send a pic or two of the control panel on this machine? There are many variations on these, and that will narrow down what you have so we can help you.
And, you’ve said high idle – what RPM? 2500?
When the coupler breaks, you don’t always hear anything, as it breaks in pieces until it can’t turn the airend.

I was unable to get to the compressor today but those are the pics my buddy sent me.

OK, thanks.
Again, I’d like to know what RPM it’s at.
Also, is it generating any pressure at all?

No it’s not generating any pressure, it just stays at a high idle, I don’t have a tach but the idle is as high as when you initially push the service air button after warm up. It turns on at that level and stays there.

Well, it’s running hi trying to make pressure.
The fact that there is none says almost for sure the airend is not being turned. Especially if you don’t get a high compressor temperature light.
There is a small chance the unloader is stuck. That’s a little orifice on the airend at the end of the intake pipe.
If you find that is open, then you just have a broken drive coupler, if you’re lucky. It’s between the engine and the airend.

Good luck.

In need of a set of doors for a 175/185 tow behind compressor please let me know if anyone out there has any or knows where to possibly get some. Thank you.

I would like to swap the Yanmar engine in my Ingersoll Rand 185 air compressor with a John Deere engine. Is there conversion instructions out there?

Maybe. There’s bolt layout…
But a lot depends on the controller. ( you didn’t give your model )
If both engines have a standard ECU, then I think it should be “plug ‘n play”.
If not, you’ll need to either rearrange the wires on the connector, or make an adapter to straighten them out.

Model Number: P185WIR / year: 2005 / Code: A
Serial# 353650UBP820

Engine family: YD3300DNMGEC
Engine Model: 4IR18N
Engine Number: R03376

Can’t find a parts diagram for the 185 we have. Need a radiator cap that has no numbers on it to help identify it. Runs the 3179 for the motor if that helps. Have the serial number but can’t find the model. Tried some of the local auto parts to match and there’s no old school people that know how to use a micrometer anymore

Is it one of these makes? 3179 doesn’t give me a clue, unfortunately.

We currently own a 2002 185 Ingersoll Rand We’re looking for a trailer kit for it Can I buy a universal one

Hi i have a 185 WIR. Any body know the difference between the WIR i have and the WJD referenced above?

It apparently refers to the hose reel, if you have one. The OSHA check valve thereon, more specifically.

The diff. Is ,,,sir,,,means it has a Ingersoll engine made by Isuzu,,,an the end,,,means it has a John Deere engine



Does an Ingersoll Rand P185 tow behind need a license plate in California?

Yes. You can get a PTI for it, I think.
That’s Permanent Trailer Identification.

My R185 is blowing smoke out of the air valve on the front, the same valve I use for my jack hammer?

I see the operator manual on this site but not the parts manual if you could point me in that direction?

Bill – look for INGERSOLL-RAND P185 parts.pdf in the IR directory if you want to put it up for Kent.

The P-185 kindly provided by Doug in is now available on this page: