Marauder Leak - Again!

[Steelontarget]

I ordered and received a custom M-Rod last August.  When I first received the rifle, I did not have a problem with leakage.  I was pleased with the rifle in every way and was amazed at its accuracy.

After a while, it started leaking.  At times it would hold pressure all week long then at other times lose about 500 psi in a 24 hour period.  I did the soapy water test around the pressure gauge and, with the barrel band removed, around the foster valve.  No bubbles.

So I figured, that the leakage had to be coming from the valve inside the foster fitting itself.  I called Crosman twice.

The Service Representatives on both phone calls had a couple of different recommendations.  The first was to ensure that I was opening the bleed valve of the pump as fast as I could to ensure that the valve was closing completely.  The other recommendation was to put a drop of silicone oil in the valve, fill it up and shoot the gun several time to fill it over again and again.  The theory was to break in the valve to get it to close completely over time.

None of those recommendations worked.  So I sent it in for warranty repair.

I got the rifle back yesterday.  The first thing that I noticed was that the barrel band was on crooked.  It was so far off that the inside of the barrel band was touching the barrel shroud!

I straightened the band and noticed a lot of silicone grease on and around the flange(?) on the end of the reservoir where the foster valve goes. 

The paper work accompanying the return merely said that the rifle was repaired.  There were no specifics mentioned on what exactly was repaired.

I used a compressor to fill the rifle then went out for the evening.  Four hours later it lost 200 PSI

I performed another soapy water test and could not find any leaks.  Because I will be using the rifle this week, I replaced the scope.  I also put a drop of silicone in the foster valve and used the hand pump till top the reservoir off. 

This morning, six hours later, the rifle lost 200 PSI

Keep in mind that I'm turning the bleed valve on both the compressor and the hand pump as fast as I can to release the pressure as quickly as possible to get the foster valve to close as firmly as possible.

I have three questions:

First, lets assume that Crosman filled the rifle up and let it sit for a few days to ensure that there was zero pressure loss.  I doubt that they really did that when I saw how haphazardly the barrel band was replaced.  Nevertheless, let's say they didn't have any problems with pressure loss after the repair. 

Now, I'm experiencing pressure loss.  So what am I doing wrong?

Now for the second question, let's assume that Crosman didn't and won't fix the problem.  I read that I can get an aftermarket foster fitting that will fit the M-rod and stop the leaks.  However, all the information that I read is old and the links haven't been very fruitful.

Can anyone provide me with a good source to find a foster fitting that won't leak?

Thirdly, is there anything that I am overlooking?  Does anyone else have any other ideas?

Thanks for your help.   

[Frank in Fairfield]

1. I would not send it back to Crosman (factory).
2. There must be a Crosman Repair facility in Ohio.
3. I you do not want to do that, remove the top end from the bottom. Remove the trigger group. Put air in the tube and leave it alone. For a week.
4. When I had my used 1720T repaired the first time it was done by a repair shop in Northern California. That is the procedure he used. If it leaked any air in that week, all (ALL) of the o-rings were replaced again.
5. You do know there is a weeper hole on the back of the gauge?

When you run out of warranty, box it up send it to motorhead...

[Steelontarget]

1. I would not send it back to Crosman (factory).
2. There must be a Crosman Repair facility in Ohio.
3. I you do not want to do that, remove the top end from the bottom. Remove the trigger group. Put air in the tube and leave it alone. For a week.
4. When I had my used 1720T repaired the first time it was done by a repair shop in Northern California. That is the procedure he used. If it leaked any air in that week, all (ALL) of the o-rings were replaced again.
5. You do know there is a weeper hole on the back of the gauge?

When you run out of warranty, box it up send it to motorhead...

Thanks for the quick reply.  All of what you said sounds good.  And all of that makes sense if the leak was consistent.  However, before I sent it to Crosman, the leak was intermittent.

Wouldn't that suggest the problem was inside the foster valve?

[bear air]

The foster valve has a little o-ring in it. When I got my 17 cal it leaked right out of the box. Luckily I had one to replace it and put the leaky one away. So fast forward several months and I won an ebay auction for a pretty rough 22 cal. The assembly had either been dimpled with a drill bit or the guy was tightening the barrel band set screws so tight it dimpled the assembly so I took the one from the 17 cal and unscrewed the fitting from the assembly and I gave it a good tap on the counter to loosen the piece inside of it. Once I had it out sure enough the o-ring had been squished and was likely the culprit to it allowing air to escape. I replaced the o-ring and put a little silicone grease on it and put some high pressure tape back on the thread and put it all back together and it was ok. You can also order a new assembly from Crosman for under 20 dollars.

[RDB]

1. I would not send it back to Crosman (factory).
2. There must be a Crosman Repair facility in Ohio.
3. I you do not want to do that, remove the top end from the bottom. Remove the trigger group. Put air in the tube and leave it alone. For a week.
4. When I had my used 1720T repaired the first time it was done by a repair shop in Northern California. That is the procedure he used. If it leaked any air in that week, all (ALL) of the o-rings were replaced again.
5. You do know there is a weeper hole on the back of the gauge?

When you run out of warranty, box it up send it to motorhead...

Thanks for the quick reply.  All of what you said sounds good.  And all of that makes sense if the leak was consistent.  However, before I sent it to Crosman, the leak was intermittent.

Wouldn't that suggest the problem was inside the foster valve?

No, could be anything. Possibly crud in the valve. If you want  to check, pull the shroud and tape a balloon over the barrel. If the balloon fills up, you found your leak. You can do the same for your fill valve.

[triggertreat]

If on the leak days, the soapy water test doesn't reveal a bubble or two, then it also could be a leaky poppet valve.  Sometimes it seals well and sometimes it doesn't sorta thing.  If it's not perfectly square, or there is some trash or foreign object between the valve seat and the poppet face, this could cause intermittent leaking when firing or opening the valve.

If I suspected a fill valve leak, I would not touch the gun after detecting that it had leaked down except to do a soapy water leak check while I knew it's leaking in its current state.

After filling, you can expect a little lower pressure reading once the reservoir temp returns back to ambient temps.  A 100lb loss is not unusual given the inaccurate gauges we are typically working with, and how heated the air became during the fill.

A troublesome leak is a good excuse to break down the gun, replace the O-rings and poppet, and learn the gun.  You'll be an expert after that.  They are a really easy gun to take apart and work on.

[Steelontarget]

1. I would not send it back to Crosman (factory).
2. There must be a Crosman Repair facility in Ohio.
3. I you do not want to do that, remove the top end from the bottom. Remove the trigger group. Put air in the tube and leave it alone. For a week.
4. When I had my used 1720T repaired the first time it was done by a repair shop in Northern California. That is the procedure he used. If it leaked any air in that week, all (ALL) of the o-rings were replaced again.
5. You do know there is a weeper hole on the back of the gauge?

When you run out of warranty, box it up send it to motorhead...

Thanks for the quick reply.  All of what you said sounds good.  And all of that makes sense if the leak was consistent.  However, before I sent it to Crosman, the leak was intermittent.

Wouldn't that suggest the problem was inside the foster valve?

No, could be anything. Possibly crud in the valve. If you want  to check, pull the shroud and tape a balloon over the barrel. If the balloon fills up, you found your leak. You can do the same for your fill valve.

I put the balloons over the fill valve and the barrel. Let’s see what happens later.

[moorepower]

I had a poppet quit leaking by shooting it for an afternoon.

[Steelontarget]

After filling, you can expect a little lower pressure reading once the reservoir temp returns back to ambient temps.  A 100lb loss is not unusual given the inaccurate gauges we are typically working with, and how heated the air became during the fill.

Initially, that’s what I thought. However, it still showed a pressure loss even with just topping off with a hand pump. The temperature in the room where the gun was at did not change.

I got balloons over the valve and barrel now. I’ll check it st the end of the day and see what happens.

[Ribbonstone]

Some ideas:



Before the long dissertation on Cromsan leaking....have bought 5 brand new Crosman PCP's over the years, and all of them have leake3d sometime in the first year...some as soon as the first month.  BAd luck?..maybe...but I've come to expect it...and (for me) 5 out of 5 have been in the gauge area (which is actually 4 possible leak points).


OK... the long dissertation:

Hunting down slow leaks is always a PIA.  Simply because it's slow, fast leaks are a whole lot e4asier to figure out.
When I'm trying the day-n-look method, will use one of those cheap dollar store kids toys for blowing bubbles (you know, the little plastic bottle with a pull out ring for blowing bubbles).  Cheap, made to make bubbles, so it works  well (although dries sticky, so clean off you test sites).

If you are really freaked out about water on your airgun then try pneumatic tool oil (can often find it pretty cheap by the pint) or the little squeeze bottles of paintball gun lube hanging on the peg boards at most sporting goods stores that sell paintball guns. (YEah...it's oil...but the PCP part is leaking OUT, not sucking in.)

M-Rod isn't real complicated, but like any PCP, there are  many possible leaks...know where is pretty key to figuring out what.
The bolt probe/barrel o-ring and transfer port can spit air during a shot, but they can't be a leak source during storage.
If the valve stem seal is leaking, it will leak down the barrel (if the bolt is closed).
The gauge area has several potential leaks (and has been my 5-for-5 Crosman leak source).
1. Gauge itself (will often bubble at the dial or at a small vent hole at the back of the gauge).
2. Threads of the gauge where is screws into the gauge block.
3. O-rings on either side of the gauge block (bubbles coming out of the hole though the air tube that the gauge passes though).

The fill cap has 3 leak areas.
1. Out the tip of the fill nipple (the little seal inside is leaking).
2. Threads where the fill nipple screws into the end cap.
3. Joint where the end cap screws into the air tube.

The valve body is sealed to the air tube and sealed with an o-ring between the valve body parts.  If those leak, they'll leak where you can't test them easily...the leak will be out the back of the valve.

The above is nearly impossible to diagnose with the typical bubble test as you need to take the rifle partly apart to get to the rear of the valve....so I I tend to check there if all the other easy possibilities have been firmly excluded (and I'm usually right).

When I'm kind of stumped by the dab-on-bubble-liquid method, and really want to trace down a slow-slow leak, will go to extremes and actually dunk the whole (pressurized) air tube.

Trigger off
Whole top end off
Rear end cap.spring.striker off.

Basically just a partly pressurized air tube (still with valve and front end cap as firmly attached as ever)...lets say 400-600psi.

2-3" of HOT water in the bath tub.

Lay the tube down and look and wait (and there is no rule saying there can only be one leak...don't just stop at the first leak you find).

OK....it's now a wet air tube. But it is also a hot air tube, so towel dry and the heat will dry the  tube much faster than any rusting could begin.  A bit rust preservative (yeah..."oil"...but it's all on the NON PRESSURIZED part of the PCP  and won't do any harm).

Remove the partial pressure (degas) before you start opening up the tube to fix the found leak(s).

Once you think you've fixed the leak, run the "dunk test" again before going to the trouble of reassembling the rifle.



IF you have a leak that is here-today and gone-tomorrow,  the two main suspects are the parts that normally move during filling or use: the valve stem (which cycles in and out at each shot and could only be leaking when it seats a certain way)  and the fill nipple seal (which also moves in and out during a fill).  Everything else is a static non-moving seal and less likely to be a now-and-again leak source (but not impossible).



Word about the gauge block system.

Actually, everything between the two o-rings sealing the gauge block to the tube is not pressurized.  The hole though the tube where the gauge goes into the block and everything between the block's o-rings is open to the outside.

DO NOT think a rifle as new as yours has a problem with that....the old ones that use the system can be (some have been running for over 10 years).    Moisture, seat, mist, dust, fog, pollen, bugs, sweat, etc. has gotten down into the center section of that Al. gauge block and oxidized/corroded it. 

As you can tell...mine get used under some adverse conditions (south Louisiana humidity/heat/and trips into salt water marshlands).
The bare-Al. will get gray...then crumbly,,,and eventually that can work it's way into the o-ring seats.

If you have to get the gauge block out...take the time to buff the bare (o-ringless block) with silicone grease.

[PG in San Diego]

Some ideas:



Before the long dissertation on Cromsan leaking....have bought 5 brand new Crosman PCP's over the years, and all of them have leake3d sometime in the first year...some as soon as the first month.  BAd luck?..maybe...but I've come to expect it...and (for me) 5 out of 5 have been in the gauge area (which is actually 4 possible leak points).

And now we know why Phil is so reluctant to crossover to the darkside! 

[Steelontarget]

Many thanks to Ribbonstone for the long dissertation.  I will re-read through it again.

I put balloons over the muzzle of the barrel and the foster valve yesterday morning around noon.  It's been about 16 1/2 hours and about 200 psi is gone.

The balloons have NOT expanded.  You can see how I attached the balloons in the photo. 

So I have either done a poor job of looking for leaks with the soapy water or it is in the internals of the gun where I cannot detect it.  The "experts" at Crosman should have found the leak.

I'm extremely upset with Crosman right now.  They have done a great job with the custom 2300KT and 2400KT airguns I bought from them in the past.  However, this rifle should be one of their flag-ship airguns and for as much as I paid for it, I should not have this much trouble.

I don't think they filled the gun up to see if it was leaking after their so-called repair.

After I calm down, I will be sending them an e-mail letting them know what I think.  It cost me a lot of money to FedEx the gun to them so I could get it back quickly in time to use it this week.

If I had known how much time and money that I would have spent on this rifle, I would have never come back over to the dark side.  Or spent extra money on another brand.

Thanks so much for everyone's help.

 

[Steelontarget]

I waited a little bit after my last posting and sent Crosman an e-mail.

I told them how upset I was and felt like they never serviced the gun like they said they did.

I told them that they should pay for the shipping as this is a brand new gun and I should not have to invest a lot of time and money to get it working properly.

I demanded that they send me an RMA number with a pre-paid shipping label.

I should not have to be repairing leaks right out of the box.  So let's see what they do.

[Ribbonstone]

IF you don't get a leak in that balloon on the fill nipple end after a day...pull it down and over the whole air tube and try a 2nd time.  That would cover the joint between the blued tube and the end cap, which can also leak. 

[triggertreat]

Sounds like now a possible nicked valve O-ring.  Easy fix to just replace the five of them at a penny a piece from The O-Ring store. #118.  Hopefully though Crosman will do you right this time around.

[bear air]

Let's hope they do. They make some good rifles IMHO but it's little things like this that turn people off.

[Steelontarget]

IF you don't get a leak in that balloon on the fill nipple end after a day...pull it down and over the whole air tube and try a 2nd time.  That would cover the joint between the blued tube and the end cap, which can also leak.

I checked that with the soapy water test.  No bubbles.

Sounds like now a possible nicked valve O-ring.  Easy fix to just replace the five of them at a penny a piece from The O-Ring store. #118.  Hopefully though Crosman will do you right this time around.

You are right.  I could probably replace every valve and o-ring in the rifle and get it to hold air.  However, it's brand new and I should not have this much trouble with it.  Crosman ought to take care of this without me shipping it to them at my expense.

[only1harry]

Did Crosman get back to you?

[Steelontarget]

Did Crosman get back to you?

I just opened the e-mail.  They sent me a UPS shipping label.  So, at least I won't have to pay for the shipping.

If I recall correctly, it's been almost 48 hours since I filled the reservoir and it's down 1,000 PSI.

I'll box it up and send it back today. 

[triggertreat]

Did Crosman get back to you?

I just opened the e-mail.  They sent me a UPS shipping label.  So, at least I won't have to pay for the shipping.

If I recall correctly, it's been almost 48 hours since I filled the reservoir and it's down 1,000 PSI.

I'll box it up and send it back today.

Good deal!  My guess is that they'll just send you another one.  Hopefully it doesn't have issues.  Take note of any blemish you can or the S/N to know what you received in return.