ALH 1.9 TDI - Plastic piece that oil pan mounts into?

Hi guys! I've been a lurker around these forums for quite a while but I recently hit the oil pan on my Jetta very hard and busted it up quite nicely. I got a replacement oil pan along with some Reinzosil D176404A2 which I've heard should seal it properly to the bottom of the engine.

After I removed the old busted pan, I noticed that a piece of plastic that had a brass threaded insert came out attached to a bolt. I attempted to remove all of the bolts from the pan prior to pulling it out but there were 2 bolts I was unable to reach by hand and they wouldn't come out by shaking the pan. I decided to loosen these bolts just as I had done on all the others and just pull the pan with the bolts still in the pan. All the bolts had a little sealant left on them which prevented them from simply falling out when they were completely loosened, so they required a very small pull and then they came right out.

A small plastic piece with the brass threading broke off, leaving behind the rest of said plastic piece in the engine. What I'm wanting to know is what this plastic piece is called and where I could buy a replacement if that's even possible? This piece sits between the engine and the transmission I believe and a few of the oil pan mounting bolts screw into it. I didn't attempt to seal the pan or fill it with oil because I believe with this plastic piece damaged how it is that it would allow oil to get onto the disk in the bell housing, which appeared to be dry. I'm quite new at working on vehicles so I'm not sure what the disk is called, the flywheel maybe?

I can get some pictures of the damage if this would help you identify what the piece is, I just thought maybe someone would know. I've got a 2001 Volkswagen Jetta 1.9 TDI with the ALH engine and (presumably) the o2j transmission. It is a 5 speed manual.

You may be talking about the rear main seal carrier, it's all one piece that has to be replaced by removing the transmission. Check this part and see if it looks right. https://www.idparts.com/rear-mainshaft-seal-a4b55-p-625.html

Video of seal replacement.

https://www.youtube.com/watch?v=Tzn4OVPSWrU

Is he working with the transmission already out? This looks like the opposite side of what I was looking at with the oil pan removed. Is there an easy way to take out the transmission alone without pulling it out with the engine?

Yes, I've changed clutches without removing the engine.

Remove axles, shifting system, battery & tray, battery cable(s), starter, clutch slave cylinder, wheels, un-clip the connector to the vehicle speed sensor (back top of tranny), and anything else I may have fail to mention. Remove all the bolts from the transmission as well as the dog-bone mount on the bottom, and then, prepare to support and drop the engine down on an angle when you are ready to remove the transmission which requires unbolting the mount bolts.

I did this by myself. I did use a cherry picker to hold and lower the transmission as well as a jack under the engine (block of wood fit on the jack and in the slot on the bottom of the oil pan).

EDIT: The piece you broke (or was already broke) located at the transmission end of the engine is oil seal carrier as already suggested by TLH_TDI. In the video, the demo is showing how to replace that seal carrier with a new seal. The transmission is out, obviously.

Hope this helps.

When I read this I interweb guessed it was the oil baffle.
https://www.partsplaceinc.com/vw-mk4-oil-pan-baffle-21917.html

Will I need any new hardware after removing certain components? I've been told I should put on new flywheel bolts after I take the flywheel off.

I did this same thing several years ago. I had a broken oil pan, I took out all the bolts lined the new pan back up and put all those bolts back in. Except for the two center ones in the back of the engine next to the transmission.

I managed one of the bolts in ok but the other I cross threaded and as I was tightening it down something broke. It turned out that those two bolts are threaded directly into the lower part of the rear seal not the engine block like all the other bolts. The rear seal is made of plastic with brass thread inserts.

In my case I managed to get enough rtv around there to prevent the oil from running out on the ground in a stream. However after that I always had a slight oil weep, until I changed the rear seal.


New flywheel bolts, new motor mount bolts, and if I was pulling off that much I would seriously consider a new clutch, throw out bearing, clutch arm, pivot pin and clip.

Thank you guys so much for the help so far!

I've done more research and I'm thinking I should also replace the bolts that hold the axle to the transmission, 6 on each side for a total of 12. I've already purchased new flywheel bolts. Please let me know if there are any other bolts I should be replacing when I separate the engine from the transmission, remove the flywheel, and replace the rear main oil seal. I may be missing steps and/or more things that have to come off with bolts in them (that maybe should be replaced if they are these "stretch bolts" that I've been hearing about). This is my very first "major" repair on any vehicle.

While performing a more in-depth inspection I noticed that the driver (left?) inner CV boot is also cracked. I've decided I'll just replace the left and right inner CV boots while I'm changing the rear main oil seal because both axles have to come off of the transmission anyways. The passenger (right?) inner CV boot seems to be just fine, no tearing, and not fragile. The car handles and turns just fine, no odd noises.

I'm tempted to do the outer CV boots too but I'm unsure if I need it. The inner CV boots are presumably exposed to higher temperatures and perhaps more stress than the outer CV boots are.

I'm also replacing the reverse light switch because my reverse lights don't work and I know the bulbs are fine. I took the switch out and put an ohm meter to it, assuming that the contacts inside would be shorted to each other when the switch was depressed, but there is no connection between the contacts regardless of the switches' state.

Also considering changing the oil in the transmission, it's never been done to my knowledge. The shifting is a bit notchy but I've also replaced the shifter counter-weight because the nut on top of the original had loosened and the gears on the original had been stripped so it wouldn't turn the spline on top of the shift tower on the transmission. I broke the little black plastic lever that holds the transmission into neutral or home position I think it was called. I put the car into first gear and adjusted the cables until it shifted into each gear properly. I've driven it a few thousand miles since I've done that and it seems ok to me, but the shifting in my brother's 01 beetle tdi (same engine and transmission) seems to be a lot smoother.

I'm unaware of the car's maintenance record before I owned it (bought at ~220k, currently has 248k). I've changed the oil at 5k intervals ever since I owned it, using various brands of oil, always 5w40 synthetic, unsure if they were on the vw qualified list of oils to use (not the best practices, I know). It has a low oil pressure light that comes on at lowish rpm when the engine is under load. Already replaced the oil pressure sensor. Also had the oil pump replaced. I taped a gauge (screwed into the spot where the oil pressure sensor would be) to the windshield and drove it around a little. The gauge started at around 70psi with the engine cold and eventually dropped to around 9psi-14psi when the engine warmed up. It's right at that pressure to be low enough to annoyingly trip the alarm on and off constantly when you are driving. I don't think it's necessarily a dangerously low pressure but it's right at the threshold, as the alarm would suggest. I've driven the car several thousand miles like this. On the highway I almost forget about the problem because when above about 1900 rpm, the alarm will never come on. Adding oil thickener causes the problem to largely disappear except at a thin rpm band in 5th gear. I'm not hugely concerned about it because I'm planning on putting a new engine in the car if anything fails catastrophically. Just wondered if anyone knew anything else I could do to prolong the engine's life or perhaps solve the problem, short of a full engine rebuild. I'm wanting to run a thicker oil, but any oil that isn't 5w40 isn't on the qualified list. Hoping someone has had a similar problem but I've yet to read about it.

jakej78b said:

While performing a more in-depth inspection I noticed that the driver (left?) inner CV boot is also cracked. I've decided I'll just replace the left and right inner CV boots while I'm changing the rear main oil seal because both axles have to come off of the transmission anyways. The passenger (right?) inner CV boot seems to be just fine, no tearing, and not fragile. The car handles and turns just fine, no odd noises.

I'm tempted to do the outer CV boots too but I'm unsure if I need it. The inner CV boots are presumably exposed to higher temperatures and perhaps more stress than the outer CV boots are.

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My luck the outer boots would crack shortly after this.

If the boots aren't to much $$ it might save the labor later.

I've used Mobil1 Turbo Diesel Truck 5W40 lately.
It has the CJ4 and CI4 rating.

jakej78b said:

I'm unaware of the car's maintenance record before I owned it (bought at ~220k, currently has 248k). I've changed the oil at 5k intervals ever since I owned it, using various brands of oil, always 5w40 synthetic, unsure if they were on the vw qualified list of oils to use (not the best practices, I know). It has a low oil pressure light that comes on at lowish rpm when the engine is under load. Already replaced the oil pressure sensor. Also had the oil pump replaced. I taped a gauge (screwed into the spot where the oil pressure sensor would be) to the windshield and drove it around a little. The gauge started at around 70psi with the engine cold and eventually dropped to around 9psi-14psi when the engine warmed up. It's right at that pressure to be low enough to annoyingly trip the alarm on and off constantly when you are driving. I don't think it's necessarily a dangerously low pressure but it's right at the threshold, as the alarm would suggest. I've driven the car several thousand miles like this. On the highway I almost forget about the problem because when above about 1900 rpm, the alarm will never come on. Adding oil thickener causes the problem to largely disappear except at a thin rpm band in 5th gear. I'm not hugely concerned about it because I'm planning on putting a new engine in the car if anything fails catastrophically. Just wondered if anyone knew anything else I could do to prolong the engine's life or perhaps solve the problem, short of a full engine rebuild. I'm wanting to run a thicker oil, but any oil that isn't 5w40 isn't on the qualified list. Hoping someone has had a similar problem but I've yet to read about it.

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get the brm oil pump, chain and tensioner, it comes with a smaller sprocket so it spins faster and moves more oil
it doesn't like continuous operation over 5k RPM though, so don't do that

oh and change your oil at 10k intervals, alh is not a picky motor that'll be unhappy with the factory recommended interval

I think I'll just replace all of the CV boots. I'm in for the long haul. Save myself some work later hopefully.

I've also decided on pulling the transmission and engine together. I'm going to be swaping both with a lower mileage set from my brother's 01 beetle which also has the alh and 5spd. This will completely solve the low oil pressure problem in my jetta. Any advice on doing a full swap to make it any easier or common pitfalls?

Is getting an actual brm oil pump necessary, or can I just get the brm oil pump sprocket and install it on the existing oil pump?

jakej78b said:

Is getting an actual brm oil pump necessary, or can I just get the brm oil pump sprocket and install it on the existing oil pump?

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eh, you've got low oil pressure so why not toss a new pump at it while it's apart? sprocket tensioner and chain ends up being like 100 anyways

It has already had a new pump installed in it just a few months ago. So I should get The brm pump, sprocket tensioner, and chain? I'm having trouble finding the brm pump online, do you know of any sources where I could obtain one?

I would not. If you were doing a pump replace maybe, but I wouldn't.

jakej78b said:

It has already had a new pump installed in it just a few months ago.

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oh then just get the sprocket and such

or since you're tossing a different motor in all together just see how that one does before you go messing around with it

I’ve been slowly working at getting everything back together. The engine swap is on hold for now. I pulled the transmission off with the engine still in the car, changed out the rear main oil seal. I had a heck of a time getting the transmission back in there but finally got it to go. Where I'm running into trouble is the axle on the drivers side won’t lift back into position. It hits the bottom of the transmission output shaft. Any tips?

Regardless of where the engine ends up I’d like to maximize its life... to a point without pouring a stupid amount of money into it. It’s gone several thousand miles with the lowish oil pressure and I believe the only problem caused is the annoyance from the dinger. I was just wondering if anyone had used a thicker oil without ill effects. I did use some Lucas oil stabilizer for a while and it cleared the majority of the annoyance. I may give the sprocket a try it definitely sounds like the best idea but I’d like to get her running again first, to make sure she still does!

Did you check your oil pickup tube when you had the oil pan off? This is what the engine I put in my daughters Jetta looked like. It’s a simple fix to clean especially if the oil pan is already off.

Recently while working on two ALH motors, one 2000, and one 2003, I noticed that there was a change in the bolt for the oil spray jet. This bolt contains a check valve possibly to just keep oil in the system while the motor is not running but in the newer motor the spring was noticeably stronger leaving me to believe that the valve would close when oil pressure dropped to maintain sufficient pressure at idle when piston cooling isn’t needed. If you have an older motor upgrading those bolts may help. Also while you had the transmission out would have been a good time to replace the main and rod bearings without removing the pistons, and that would have given you better oil pressure.


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I did inspect the oil pickup tube, it was quite clean. I only have a few bolts in the oil pan right now and I haven't got sealant between the pan and the engine yet, nor have I added any oil back into the pan. The pan coming back off is not a big deal at all.

Are there any specific online retailers that are good quality or ones to avoid? I found bearings on kermatdi, idparts, performancebyie, and partsplaceinc. Not sure who to choose.

Kerma or ID, have not heard of the others.

Got everything back together and it runs and drives! I am now encountering a violent wobble while decelerating and I'm mystified as to what the cause could be. Any ideas? It doesn't seem to matter if I'm in gear or not while decelerating and it only happens when decelerating from speeds greater than 30mph.

Could be a CV joint.


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did you unbolt the dogbone mount?

I completely removed the dogbone mount. However, I believe it has been properly reinstalled. I think I can safely rule out the dogbone mount as I recently had one break on me and I replaced it with this new one and never noticed any wobbling until this latest teardown and reassemble.

Both the inner CV boots are torn however there was no noticeable wobbling previously. The axles sat disconnected with no protection for over a month. Could contamination in the boot area ruin the joint after less than 10 miles of driving? I'm unsure if the axles went back on in the exact same holes they were previously, my markings had worn off by the time I got back around to hooking them back up. Is axle imbalance possible? OEM axles.

axles aren't fast enough for imbalance to be a concern

generally it takes a while for dirt in the joint to cause wear, and that'll usually be on the drive side of the joint, not the coast side
besides, you state the shake is the same clutch in or out, while a change in power transmission will usually affect a CV joint shake
front end components are all tight? Easy to leave a lower ball joint loose in the control arm or something

As far as I know none of the suspension has been changed or taken out. The car drove perfectly before I did any work to it. I did the following: Disconnected both axles from the transmission, left the axles connected on the other side. Disconnected the shifting linkage from the transmission. Removed the transmission from the car to replace the rear main seal. The clutch and flywheel both came off, then I put them back on, put the transmission back in, and reattached the axles.

TLH_TDI said:

Recently while working on two ALH motors, one 2000, and one 2003, I noticed that there was a change in the bolt for the oil spray jet. This bolt contains a check valve possibly to just keep oil in the system while the motor is not running but in the newer motor the spring was noticeably stronger leaving me to believe that the valve would close when oil pressure dropped to maintain sufficient pressure at idle when piston cooling isn’t needed. If you have an older motor upgrading those bolts may help. Also while you had the transmission out would have been a good time to replace the main and rod bearings without removing the pistons, and that would have given you better oil pressure.


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Old post sorry but I have to ask you. I just had my engine rebuilt. I'm not familiar with ALH but the mechanic used parts of my ALH engine 03 and parts of his ALH engine, not sure what year. He said the lower end is from his and the cylinder head is from mine. Also the oil pump is from mine. Now the issue I'm having is low oil pressure, some misfire and a bit of smoke around the engine. He checked it with e mechanical gauge and said it was good. I already changed the sensor. Can this be my issue ( difference between years of the oil spray jet )

Argjent said:

Old post sorry but I have to ask you. I just had my engine rebuilt. I'm not familiar with ALH but the mechanic used parts of my ALH engine 03 and parts of his ALH engine, not sure what year. He said the lower end is from his and the cylinder head is from mine. Also the oil pump is from mine. Now the issue I'm having is low oil pressure, some misfire and a bit of smoke around the engine. He checked it with e mechanical gauge and said it was good. I already changed the sensor. Can this be my issue ( difference between years of the oil spray jet )

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It could be, but anything on my part without me tearing the motor down is just speculation. You could try an upgraded oil pump before going to to much trouble. https://www.cascadegerman.com/product/vw-alh-tdi-oem-oil-pump-upgrade-kit-99-03/ Oil pressure though, would not cause a misfire.