1999 ML320: Where is my oil cooler??
 

I have a 1999 ML320. I believe WIS says my VIN has a w163 112.

I am systematically going through and replacing gaskets that may be leaking. I've done the valve covers and breather covers, and am now trying to do the oil filter housing. I bought the gaskets before I realized that there is no oil cooler attached to it and it is different than virtually every diagram I can find for the early ml320.

Do I actually have an oil cooler somewhere else, or do I not have one at all? What is the model number for the models without an oil cooler, so I can differentiate it from all the pictures I see and so I can order the right parts? Are there instructions somewhere for replacing the oil filter housing seal without the oil cooler? It seems rare, because almost every picture I can find when I search for W164 ml320 shows an oil cooler attached to the filter housing.

I've had the ml320 for a trouble free year and I am otherwise new to mercedes so I may be missing something with how the engine numbering works?

Thanks for any help.

Welcome sdw163,

Can you post some photos of what you have?

See this - yours should look like this, yes?

https://cimg2.ibsrv.net/gimg/www.mbw...5aa73a42c0.jpg
This is mine. Note the oil filter housing is round and there is no oil cooler attached to it between it and the top radiator hose.

https://cimg9.ibsrv.net/gimg/www.mbw...c32a92c68f.jpg
This is what I see in the shop manual and in almost all pictures I find online, where the oil filter housing has a flat side that mates with the oil cooler, and the oil cooler takes up the space between the radiator hose and the oil filter housing.

Yup, I found that old thread after I posted and it references another old thread. A lot of conflicting info, but the right answer appears to be that the oil cooler was always included in non-US models, but in the US for V6 it was only included in 1998 and early 1999 through 30 03310. Apparently My ML320 is 30 42???, so it does not have an oil cooler. It's confusing because there is no indication I could find in the WIS of any model without an oil cooler, but someone posted a shot from the EPC where the oil cooler part has a note that it is only applicable in the US through the listed number. It is confusing since the WIS diagrams can be found online, but the EPC note typically is not.

Why was the oil cooler removed from US V6 early on, but not anywhere else?

Backstory: My ML320 has 170K miles and has developed some leaks. Recently a more dramatic leak developed. It's hard to tell exactly where because of the amount of oil and that it has been spread by the belt. The valve covers are definitely leaking, but there seems to be a bigger leak near the oil filter housing. I am making a pass through to replace the most obvious old gaskets and hoses. I am replacing valve covers, resealing the breather covers, replacing the breather hoses as well as the radiator hoses and the timing case expansion cover. After everything is replaced and the engine cleaned, I will be better able to see if there are any other leaks.

The gaskets between the oil filter housing and the oil cooler are known to leak. Is this also a problem with the models without an oil cooler? Now that I know to follow the note, it looks like there is not even a part for the oil filter housing in the US models, but that the oil filter housing is an integral part of the timing case. Is there anything additional in the US models that could leak that I should address?

Deleted.

only the v8's and non US delivered ML's up to 02 had them.

Vin #?

4JGAB54E7XA112439: = 30 427219

No, I hadn't seen that thread. The OP in the thread went through the exact same progression as I did. Bought the 46mm socket and seals for a job that doesn't exist, and then slowly circling around figuring out more and more about which engine numbers in which markets actually had the oil cooler. That seems like an odd difference to me, so I wonder what else may be different in that engine? It doesn't seem like an emissions issue, but I can't think of why else it was different in different markets.

Now I'm in hurry up and wait mode for the screw and washer that goes in the timing case expansion plate and crush washer, because I didn't realize they didn't come with the new expansion plate I ordered. Coincidentally it is literally the same part as the transmission drain plug! What is the purpose of the expansion plate? Is there something behind it that needs access?

I honestly dont have any idea why?

Maybe Maj. Dundee or one of the other vets more familiar with these V6s in the MLs can chime in? :) :bow:

khomer, what expansion plate? Never heard of one. This thread is all about oil filters and oil coolers.

Maj. Dundee, This is Q from sdw163. I believe he's now asking another Q on this expansion plate.

sdw163, what say you?


https://cimg6.ibsrv.net/gimg/www.mbw...b7ca20d2a8.jpg

yup, that is it. I'm replacing it to get rid of an oil leak and I noticed that the center bolt and washer are literally the same part as the transmission drain plug. That made me wonder why it is there and what it is for?

Are you sure that's (another) source of your oil leak?

Here's more info in my leisure reading for tonight. :)

EDIT - your answer to your Q, post 16.

That part is called the Oil Pressure Test Port. Expansion Plate was a made up name and it stuck.

not 100% sure, but seemed to come from that area. Since I don't actually have any oil filter housing gaskets, the oil pressure port seems most likely and is easy enough to go ahead and try. With the fan, fan shroud and belt removed, I can also much better clean the front of the engine to better find any other leaks. As I said previously, I also replaced the valve cover gaskets and resealed the breather covers.

I bought it knowing it had a slow leak. Perfect condition but owner couldn't park in their garage anymore. Original owner and well maintained, but they were not mechanical. They were told the pan leaked. The pan may be leaking, but hard to tell yet because of the other obvious leaks higher on the engine.

I drove it for 20k before the leak suddenly got much worse, so now I am addressing it. The one other problem it came with is it would rarely start the first time. That seemed very much like the pressure regulator in the fuel filter, so I didn't worry too much about it right away. I did finally replace the fuel filter along with new fuel lines because it was the old style and obviously had never been replaced. It made a big difference in starting and seemed to run a little better, but the oil leak got much worse within 300-400 miles. I don't know whether there could possibly be any connection. The one other thing that happened shortly before the leak got worse, is that the idler pulley broke and shredded the belt.

Thank you! That makes infinitely more sense.

You have to clean the entire area of the engine where there is oil and then run the eng. to see where leak is coming from.

The oil pressure test port is well known for leaking with age.

All back together, I've driven it in progressively longer tests for 30-40 minutes, and no sign of any oil leaks yet. Yay!

It is idling a little rough. Not horrible, but enough that I can tell it is not quite right. I replaced all of the crankcase ventilation breather hoses and the ring seal for the air intake housing at the rear of the engine. Would a leak there be enough to cause the rough idle? I didn't really touch anything else, except in cleaning. There are no warning lights.

Yes. A vacuum leak on a line with a crack you cant see?
Clean your MAF.
sparkplug wires? coils? what about a scan?

I have not seen a check engine light since I put it back together. I've probably started it 10 times and run it for 40 minutes. I just took out my reader, and due to your power of suggestion, the CEL came on for the first time. P0170 and P0173, fuel trim.

The MAF was obviously replaced at some point, but not by me. It has a newish looking barcode sticker on it so it doesn't look original. I replaced the spark plugs 2 years and 18K miles ago. Spark plug wires and coils have not been replaced by me, but they were removed to replace the valve cover gaskets.

I'll clean the MAF.

I cleared the codes and started it 3 more times running it 5 minutes each time and the codes have not come back.

not my fault with the PoS... :nix:
Non-OEM MAFs are known to cause hiccups as you are probably well aware of. :)
AND.....
common cause of P0170 P0173 is a defective mass-airflow sensor. Cleaning hopefully resolves this and saves you a bit of $$.

I am pretty sure I need a new MAF. Proved it by cleaning it poorly! I cleaned it with MAF cleaner and ran it before it was dry, thinking the air flow would dry it quickly. Drove my wife to the doctor and it idled and ran much more smoothly. After her appointment, it idled rough and ran horribly. I found a reference that said disconnecting the MAF completely will cause it to use a default trim that will run better than a faulty MAF. I disconnected the MAF, and sure enough it ran better again. I think the wet MAF must have been malfunctioning and when it dried it starting "working" again and sending bad data.

I know that non-OEM MAFs can cause hiccups, but they are also dramatically less expensive. Are there any known to be better than others? I'd rather spend $40 to prove whether the MAF is really the problem and replace it if it doesn't last, than pay $140 for OEM and find out it isn't the real problem.