Failed tandem pump can cause oil to mix with fuel

kpiazzisi

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It's in the VW manual, but no one that I have asked so far has been able to substainiate weather or not a failed tandem pump will cause oil and fuel to mix.

I have several post on here, and I am sad to say I have had a lot of problems with my TDI. Most of the problems were my fault. I know my tandem pump has failed. I have been dealing with it, and so far have not ponyied up the 400 bucks for a new pump.

I have been having a seperate issue, which is intermitient white smoke. I tried almost everything to resolve the white smoke issue and have several posts on here asking for help troubleshooting the smoke issue.

One thing I noticed is that an oil change seems to resolve the smoke issue. Yesturday when I drained the oil, I have over 5 quarts in the drain pan. I believe I only put in 4 quarts when I changed the oil a couple of months ago.

In my opinion, I belive fuel is mixing with the oil just like it states in the VW manual. IF YOUR TANDEM PUMP IS BROKEN, I WOULD NOT SIMPLY BUY AN EXTERNAL CHECK VALVE. I WOULD REPLACE THE PUMP.


"The tandem pump must be checked for internal leaks between fuel side and oil side after reinstalling a used tandem pump, for example after renewing or repairing a cylinder head and/or when installing a “short” engine. When leaking it is possible for the fuel to mix with the oil, which may cause the engine to fail. "
 
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VWBeamer

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I believe just seals can be replaced on the IIRC, anyway it's certain that fuel in the oil will cause damage to the engine, the PD motor is already hard on cams. Not to replace or repair the pump seams penny wise, dollar foolish.
 

Henrick

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How can I know my TP is faulty and probably leaking fuel into oil? What symptoms to watch for?
 

Ol'Rattler

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To the OP, you got the title backwards. Should read: "Failed internal Tandum pump seals will cause fuel to mix with the crankcase oil."

It's in the VW manual, but no one that I have asked so far has been able to substainiate weather or not a failed tandem pump will cause oil and fuel to mix.
I think Bentley's answered you question pretty clearly, however, there are other things that may cause fuel to leak into the oil.
One thing I noticed is that an oil change seems to resolve the smoke issue. Yesturday when I drained the oil, I have over 5 quarts in the drain pan. I believe I only put in 4 quarts when I changed the oil a couple of months ago.
I think you answered your own question. The oil level rising is a sign of either coolant or fuel getting into the oil. Coolant in the oil will turn the oil green, white or brown were as fuel in the oil will not change the color of the oil. All you need to do know, is confirm the leak per the test called out in Bentley's for the T/P.
In my opinion, I belive fuel is mixing with the oil just like it states in the VW manual. IF YOUR TANDEM PUMP IS BROKEN, I WOULD NOT SIMPLY BUY AN EXTERNAL CHECK VALVE. I WOULD REPLACE THE PUMP.
Were did you get the idea that adding a check valve would help in this case? Where a T/P will leak fuel is past the drive and into the area under the valve cover. A check valve would have to be installed inside the Tandum pump. Something that would be close to impossible to do.

Great job on getting a manual and sitting down and trying to understand it. You are right to keep asking questions until you fully understand something because with this technical stuff, the devil really is in the details.
 
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PDJetta

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Last year I replaced my tandem pump and it was $250 and about $14 shipping from 1stvwparts.com (a true VW dealer with internet sales that knocks about 40% off of dealer retail). (I had a slight external fuel weep/drip that I later concluded was the $10 mounting gasket, but I am glad I replaced the pump). As far as I know, the BEW (my '04's engine) and the BRM tandem pump are the same part number. The original LUK pump was a vane fuel pump and had the wiggly/loose vacuum port and the new pump is a Bosch gear type pump and the vacuum port is threaded into the pump and is solid.

Anyway, a failed inner seal on the tandem pump absolutely can introduce diesel into the lube oil. I just posted this the other day in another thread:

"The tandem pump can do this (leak fuel into the engine). I read that one person had it happen and when I dissasembled my old tandem pump, I saw how it can happen. A common shaft through the pump drives both the fuel pump and vacuum pumps (driven by the camshaft). The vacuum pump is inboard (next to the cylinder head) and sucks air in through the big brake booster line port and exhausts the air into a hole in the side of the cylinder head that is drilled through to the oil sump (a small amount of lube oil is exhausted with this air too. The oil lubricates the tandem pump from another, small, galley from the cylinder head). Anyway, the fuel pump chamber sits outboard and there is a simply garter spring seal that seals the shaft between the two pumps. If that seal fails, fuel will be sucked into the vacuum side of the temdem pump and will be exhausted into the cylinder head and it will then run down the head oil return passage and into the oil pan."

If any doubt exists, I would spend the approximately $275 and replace the tandem pump. The Bosch pump is quite nice.

As for the white exhaust smoke, I would verify that the valve timing is on
(check the "torsion value" with a VCDS, should be near to 0.0 degrees) and also closely inspect the camshaft and lifters for wear.

--Nate
 
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PDJetta

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How can I know my TP is faulty and probably leaking fuel into oil? What symptoms to watch for?
If the oil smells of diesel (and the oil level rises over time) its a sure sign. Absent that, one sure way to determine if you have fuel dilution is to send an oil sample to Blackstone Labs. One item in the report is "% Fuel in oil". They will send you a free sample kit before hand.

http://www.blackstone-labs.com/

Another source of fuel in the oil can be bad injector O-rings, so fuel in the oil does not automatically mean the internal seal in the tandem pump has failed. But its far easier to replace the tandem pump than the injector seals. The seal kit for each injector is about $35, IIRC. So you's spend about $140 to replace all four sets. That's almmost half the cost of a tandem pump and a heck of a lot of labor.

--Nate
 

kpiazzisi

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tampa, florida
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jetta 2006
I just ordered the pump. It is not that I am Penny wise and Dollar foolish, it's just that I don't want to drop $300.00 for a part not knowing if that's going to resolve the issue or not. These posts are exactly what I needed. PDJetta, TY for providing the explanation I was looking for. Here is the part number that I purchased. Can someone plz verify that it is the correct part. I got a great deal on the pump. It's a pierburg and not a Bosh? is that OK. I think there are some rules on here where one can not disclose price or exact details on parts, but plz PM me if this will not work and I will provide the details.

2004-2006 Volkswagen Jetta Mechanical Fuel Pump - Pierburg
with FREE Shipping
Quantity:
Select Year 2004 2005 2006


Part Number: W0133-1918679
Notes: Located on Engine
Detailed Notes: Fuel and Vacuum Pump
Brand: Pierburg
 

JB05

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I wonder if there is a way to check the tandem pump to verify that it is leaking.
 

PDJetta

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I've never heard of a rule on the list not to divulge parts sources or prices. If I get a good price and am happy, I pass the info along.

Pierburg is OEM too. VW used tandem pumps from LUK and Pierburg in the factory and I think the Bosch I got was to replace the LUK supplier. Your Pieburg is fine. I just googled on the part number you supplied and it brought up where you got it. You got a great deal too.

VW had a recall a few years ago for a certian VIN range (certain 2004 and 2005 models, split accross the two model years) to replace the LUK tandem pump with defective fasteners and the replacement was a Pieburg pump.

--Nate
 
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Henrick

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Okay.

Let's clarify a few things.

Blackstone labs is probably limited to North American market so it's not an option for me being on the other side of the pond.

I have never messed with injector seals nor injectors themselves. There are 5 seals for each injector if I remember correctly. So those should be fine and prevent fuel dillution.

My Tandem Pump is LUK. It's the original one, never messed with it too. I see some fuel sweepage on the outside. Is that a reason to replace the pump? Should I start worrying? :(
 

Henrick

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Oh, and my oil level does not rise. At least at that rate for me to notice. Since I idle much, I burn some oil. Maybe the excess is just passing through the turbo seal?

And it's hard to describe the smell but I think the oil smells like popcorn (I'm using Motul and it's 505.01).
 

Ol'Rattler

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I wonder if there is a way to check the tandem pump to verify that it is leaking.
Well, ya. It was mentioned in post #1 and post#4. Anyway, Bentley's has the procedure for checking for leaks from the fuel side to the oil side of the Tandum Pump.
 

PDJetta

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Okay.

Let's clarify a few things.

Blackstone labs is probably limited to North American market so it's not an option for me being on the other side of the pond.

I have never messed with injector seals nor injectors themselves. There are 5 seals for each injector if I remember correctly. So those should be fine and prevent fuel dillution.

My Tandem Pump is LUK. It's the original one, never messed with it too. I see some fuel sweepage on the outside. Is that a reason to replace the pump? Should I start worrying? :(
I replaced my LUK pump because of fuel weepage, but I think it was the (replaceable) $10 mounting gasket that was leaking. If the top cover gasket is leaking, I would replace the pump, or if you are getting fuel in the oil, in the hopes that it is not an injector seal.

--Nate
 

kpiazzisi

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tampa, florida
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jetta 2006
OK I replaced the pump, but the new pump still looses prime



The new pump is still loosing it's prime. I took it apart and I am not seeing a check valve anywhere?
I heard there is a check valve in the tank, is this the only check valve there is? Napa actually sells
a check valve for a 2006 jetta TDI for about 30 bucks. I also found some oil in the vacuume side of
the pump. I am thinking that this should not be there? What do you think?
 
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kpiazzisi

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Update. After replacing the Tandem pump, the problem continued. The tandem pump still lost it's prime. I inserted a check valve on the supply side of the fuel line and the pump still lost it's prime. The only way the pump would not loose its prime was if I clamped both the supply and return line near the tandem pump. I noticed using the VCDS tool that I also had a high injector deviation for cylinder #2 of about 2.5. I suspected that possibly the injector was not seated properly or a had a bad injector. I swapped injectors #1 and #2 thinking I would at least be able to see if the injector deviation followed the injector. I was pleased when my car started running smoother. No longer is the pump loosing it's prime. No more rough idle. No more smoke issues. No more injector quantity deviation. Everything seems to have been resolved by swapping the injectors and in the process re-seating the injector. I bought new o-ring seals when I changed the cylinder head months ago, so I am not sure why cyclinder injector #2 did not seat properly, but it has caused my all kinds of grief. I think the smoking was caused by oil from the head leaking past the o-ring into the cylinder. This probably mixed with diesel creating a slurry that could not combust. Some of it went out the exhaust in the form of black smoke and some of it slipped past the rings into the oil pan.

The car has been running great now for a week! If anyone has the issues that I have had, you might want to make sure your injectors are seated correctly. This is probably more of an issue if you removed them as some point like I did during the install of the new head.

Take Care
KP.
 

PDJetta

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Good job figuring that out. The injector probably would have been the last place I would have looked. I think you are correct on your analysis of the cause.

--Nate
 

kpiazzisi

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Thanks. People were probably tired of all my threads on here, but I was seriously just trying to get help. The car is still running smooth, so the improperly seated injector must have been the problem.

Take Care
 

readyrangers

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2004 A3 140 tdi sport
Hi i have been reading through this thread,i have a problem the opposite way round. I am getting oil in my diesel,i have been told it is the tandem pump.Is it possible for it to be pulling the oil from the engine into the diesel? I have an Audi a3 2.0l tdi.
Thanks
 

PDJetta

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There is a garter spring type seal that seals the drive shaft in the tandem pump. The vacuum pump cavity is inboard and the fuel pump is outboard. They share a common driveshaft, driven by the camshaft. The vacuum pump is oiled via a galley in the cylinder head, but is under a negative pressure and the fuel pump has a positive pressure, so a leaky shaft seal should cause diesel fuel to leak into the vacuum pump cavity and be exhausted into the cylinder head pump exhaust port and drain into the oil pan. So I don't think it is possible.

--Nate
 
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