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Sanden 709 seal replacement

Diesel Power on Wed June 30, 2010 12:59 AM User is offlineView users profile

Year: various
Make: Peterbilt, Freightliner
Country of Origin: United States

Hello,

I'm new to the forum so first I will say hello to everyone. I work mainly on heavy truck/tractors and run a mobile repair service. In the last few years diesel engine technology has changed quite a bit to help cut down on particle emissions. One thing that has drastically changed under the hood is the temperature, it has gone up. In addition to engine belts and hoses (most anything rubber) deteriorating faster than it has ever before I have noticed a large increase in front seal's leaking on Sanden 709 compressors. I suspect it is mainly due to the increase in under hood temperatures as I have never really had a problem with them before. A example of a Sanden 709 compressor I'm currently looking to replace the front seal on is a Sanden #4432, model 7H15HD which is on a 2008 Peterbilt 335 with a C7 Caterpillar diesel engine.

What I'm looking for is a little info on seal replacement. I could easily just replace the compressors but that tends to get a little expensive for the customer when it's really only a couple of dollar seal that is bad. My problem is I can't for the life of me find a Sanden 709 seal service kit. There's plenty out there for the 500 series but none that I can find for the 708/709 series. Is there one? I have a seal lip protector that slides over the main shaft to protect the seal during installation but what I really need is to find a seal remover. Does anyone make such a critter or am I going to have to spend some time in my machine shop fabricating my own?

Also, I ran across this post on 709 compressors and was curious, is this front cover seal available? I have also had a few that were leaking from this o-ring. Like this post original poster all I can find is the rear head gasket kit with no front cover seal. Another question related to seals is, is there a premium seal manufacturer out there. I pride myself on doing the job right the first time and don't mind paying a little more for quality replacement parts. I'm a firm believer in you get what you pay for.

I look forward to the forum's comments on my predicament.

ice-n-tropics on Wed June 30, 2010 2:04 PM User is offline

Power,
There is a lot to rant about on Sanden front shaft lip seals, but there are A/C system integrity and compressor design issues also.
Seal life-
The standard Sanden seal is built for about 100,000+ miles on a truck duty cycle (w/ sleeper) on a standard Sanden compressor.
Higher underhood temps should not shorten seal life.
The internal compressor crankcase temperature is the main factor on seal life. Lower than spec. refrigerant charge raises the crankcase temperature.
Internal oil circulation to the seal is an important life factor.
Sanden has a "Heavy Duty" more expensive compressor with a improved drilled oil passageway to cool and lube the seal and it has a 3 year warranty to the OEM. It also has a better lip seal.
Seal service-
The OEMs don't want anything to do with shaft seal replacement because there is no profit as compared to a compressor replacement, therefore no service tools have been developed.
Usually the 2 bit lip seals can be extracted using 2 medium/small blade screwdrivers in a relative "X" relationship with the tips just under the seal's metal shell ID. Then wedge the screwdrivers against the inside edge of the cast iron front compressor nose and pry out the seal. On rare cases it may be necessary to drill a little hole into the seal metal case and use a hook to yank out the seal.
The newer seals do not have a "O-ring" between the seal and the iron front compressor housing. The o-ring is replaced with rubber molded on the outer surface of the seal's metal housing.
The felt ring is installed to absorb any refrigerant oil that seeps between the seal rubber lip and the shaft. This reduces the oil that could reach the clutch friction surfaces and cause the clutch to slip and fail.
Clutch failure with hot slip will smoke the shaft seal.
Caution:
Always be careful not to scratch the shaft.
Inspect your tapered shaft seal inspector cone installation tool for scratches or any sharp step. It needs to be polished.
Clean out the compressor front housing nose real good.
Flood the new seal and installation cone with mineral refrigerant oil during installation.
Cordially,
hotrodac

-------------------------
Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

HVargas on Wed June 30, 2010 2:09 PM User is offlineView users profile

As far as the seals go, yes there are replacement seals available for those compressors. The SD7H15 and SD708-709 compressors do you different seals so your best bet is just to give us the Sanden number and that will tell us everything we need to know. The 4432 comes up as a SD7H15 and we have a seal available for that. 21-34702. As far as tools for replacement. The Sanden SD708-709 tools only show to be available in a master kit that runs $499.98. I am sure there is a tool available and I will have to call Mastercool for that info.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: Arizona Mobile Air

Diesel Power on Wed June 30, 2010 4:00 PM User is offlineView users profile

Thanks for the replies. Ice-n-Tropics -- The majority of the vehicles I'm having the front seal problem are not road tractors but medium duty trucks. The one I used as a example is a Peterbilt 335 which is a medium duty tow truck. I sure wish my customers could get 100,000 miles of life out of them. The truck in question only has 44,000 miles on it and does not have a sleeper, just a conventional cab A/C system. I get the feeling some of the problem with this type truck (and it's not just Peterbilt) is that they have redesigned the hoods for better visibility from the drivers seat which has also reduced the under hood area along with the additional air that use to surround the compressors and helped to keep them cool. It's a combination of reduced air circulation under the hood along with greatly increased engine temps that seems to be killing them. Not to mention they all but set on top of the exhaust manifolds on many engines with hot EGR lines directly behind them. The compressors use to mount on the drivers side of the engine all by themselves and now are mounted on the passenger side which is a oven compared to the drivers side.

Looks like I'll have to spend a little time back in the machine shop and design a seal puller for the front seal. From the looks of it I will be changing these quite frequently and the correct tool for the job sure speeds up service time.

HVargas on Wed June 30, 2010 5:40 PM User is offlineView users profile

Depending on your location, shaft seal leaks can be common depending on the use of the compressor. I would make sure to tell the guys driving the trucks that in the winter months or when they aren't using the A/C to kick it on every couple weeks for 10-15 minutes to keep that seal lubricated. The heat coupled with not being run for a while will wear that seal out pretty quick.

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: Arizona Mobile Air


Edited: Wed June 30, 2010 at 6:06 PM by HVargas

Diesel Power on Thu July 01, 2010 1:27 AM User is offlineView users profile

I doubt it's lack of use in the winter month's but was a good idea none the less. The compressor comes on in medium/heavy trucks with the defroster's just like light duty p/u's and cars.

HVargas on Thu July 01, 2010 2:02 PM User is offlineView users profile

How bad do the shaft seals look that are coming out? Are they torn and cracked or just worn out?

-------------------------

When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: Arizona Mobile Air


Edited: Thu July 01, 2010 at 2:07 PM by HVargas

ice-n-tropics on Thu July 01, 2010 6:56 PM User is offline

Power,
You have sparked our curiosity on a seal which fails at 44,000 miles, but the following may be a little boring.
Dual lip[ seals have a teflon lip (on the vehicle rear side) which stops outside air from entering the compressor during vacuum service. The other (front) lip member is rubber and stops positive pressure refrigerant leaks.
Grinding marks from centerless grinding on the shaft have a particular lay. Since the shaft rotation is CW (on all except Honda, Iveco and some VW diesels) the shaft groove pattern is CCW for the purpose of dragging seeping oil back into the compressor(like a miniature pump). The grinding spec is checked by chucking the shaft in a lathe chuck. Next a monofilament fly fishing lone with weighted ends is hung on the shaft. The chuck is turned and the moving direction and groves per inch (number of chuck turns per inch of line travel) is measured
If you want to analyze the seal failure:
1) remove the compressor and mount it vertically with the shaft end up
2) Remove the clutch and inspect clutch for clutch induced overheating which will smoke the seal.
3) Pressurize the compressor with 30 to 50 psi
4) Put a 1/4" thickness of oil on top of the seal
5) Look to see if the leak bubbles originate between the shaft and the lip seal contact interface (seal tear or rubber lip wear out) or if it bubbles around the outer edge of the seal OD (external heat due to hot clutch or hot engine location). If there are no bubbles turn the shaft very slowly to find a position that leaks. If still no leaks then bubble check the joint between the black iron fronted housing and the aluminum housing for a o-ring leak which fooled us into blaming the seal.
6) Release the pressure and remove the seal
7) Wear out can be seen with a magnifying glass or better with a microscope looking at the rubber lip and shaft for wear.
If A/C was 30% or more undercharged the seal can fail due to internal compressor overheating.
Cordially,
hotrodac

-------------------------
Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

Edited: Fri July 02, 2010 at 10:58 AM by ice-n-tropics

bohica2xo on Thu July 01, 2010 9:03 PM User is offline

Tex:

The SD709 in my work truck is original - 1993 dealer installed A/C . It recently went from "crappy" (I really need to look at that when I have time, don't turn it on) to "no pressure" in the space of a week or so when I got the gauges on it. Ordered a drier & some other stuff from Tim.

Watching this thread made me think uh oh, probably a shaft seal. Since the design is "100k" and the truck is over 150k I figured it might be time... Especially since it has been idled for extended periods. It has a lot of hours.

This afternoon I put some N2 in it to look for the leak, and went straight to the compressor. I could hear it. NOT a shaft seal. Just a loose flare fitting. Not the first ford I have found like this either. High side, so I know it lost plenty of oil too.

Flushed the system, recharged oil & refrigerant - and the SD709 soldiers on. I fully expect to get close to the 200k mark from that compressor, perhaps more.


Diesel Power:

I have proven 709's are tough units. Stop & go traffic with 115f ambients, short trips. Idling. Straight from the traffic to the freeway. Much the same service as a tow truck.

Perhaps a heat shield would be in order on the C7 install. The compressor can transfer heat to the refrigerant when it is running, but if it is baking with IR heat year round it will not do well. Insulating the EGR lines is a possibility as well. 709's do need oil. A low charge will starve them, so make sure the system has enough oil & refrigerant.

Are these systems CCOT, or TXV type?

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

TRB on Thu July 01, 2010 10:20 PM User is offlineView users profile

Quote
Originally posted by: bohica2xo
Ordered a drier & some other stuff from Tim. B.

and we thank you for the support!

I had some issues with the Sanden shaft seals! Many were on the 507 model. Even so I would use a Sanden over many other compressor brands any day of thew week.



-------------------------
When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

ice-n-tropics on Fri July 02, 2010 11:29 AM User is offline

The Class 8 trucks can get lots of idle sleeper A/C comp operation.
44,000 mile truck owner could get free warranty compressor.
Tim
Your 507 problems were probably 15+ years ago with carbon mechanical face seals and comp made in Japan.
Pal 2xo
Ya got one of them its'y bits'y Ford PUs that don't have room for a gun rack? I got a big O'l tall Ram w/ 20" wheels. Keep the scatter gun tucked down behind the seat. Gun in the trunk is no help as I found out between El Paso and Carlsbad when crook tried to curb me at 1 AM. I out ran him uphill.
Got the drop on 3 tire thiefs with my scatter gun. Forth guy ran away and escaped. Told then to keep both hands on the hood and that my trigger finger was shaking. All 4 tires were in their car already. Don't know where they though they could sit in their car.
Cordially,
hotrodac

-------------------------
Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

TRB on Fri July 02, 2010 11:35 AM User is offlineView users profile

Quote
Originally posted by: ice-n-tropics
Tim

Your 507 problems were probably 15+ years ago with carbon mechanical face seals and comp made in Japan.

No these were batches a few years back. Been better lately and still am not complaining. Overall Sanden makes a good compressor.



-------------------------
When considering your next auto A/C purchase, please consider the site that supports you: ACkits.com
Contact: ACKits.com

bohica2xo on Fri July 02, 2010 12:59 PM User is offline

Hell Tex, you are slippin'. After dark in TX it is a good shoot if the varmints are runnin' away.

If you have a smaller toolbox, you just buy more compact tools. I keep an RFB behind the seat, and a half dozen magazines for it. 7.62 goes places 00 will not...

Dunno about them 20" wheels, I usually see those on an old Monte Carlo around here. Last time I had to buy 15" tires it was only a couple hunnert bucks too...

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

ice-n-tropics on Sat July 03, 2010 10:46 AM User is offline

Brad,
I didn't want to shoot the runaway varmint over tires because I stole some steaks when there were hard times. Maybe he needed tires to get a job and those little bitty tires cast hundreds. It's hard to pull the trigger when he can't hurt me.
hotrodac

-------------------------
Isentropic Efficiency=Ratio of Theoretical Compression Energy/Actual Energy.
AMAZON.com: How To Air Condition Your Hot Rod

Edited: Sat July 03, 2010 at 11:29 AM by ice-n-tropics

bohica2xo on Sat July 03, 2010 6:14 PM User is offline

True enough Tex. I would let the runner go too.

Now, if he had a can of spray paint...

B.

-------------------------
"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

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