My engine is has made it 240,000 miles and is now on it's last leg. I have not removed the head to see it's damaged the piston yet. At this point I have lots of "blow-by" when I remove the oil cap while the engine is running (like a choo choo train...).

Rather than replace/rebuild the head and/or piston, I'm considering replacing the long-block engine. I can get an engine from a '96 E320 for around $1600. I already know that I'm going to need to swap my oil pan, oil sump, water pump, and external accessories.

Have any of you already done this (with the G320 M104.996 engine)?

Are there any other concerns that I should have?

Can I swap with the AMG 3.6L engine and ECU (If I can find one)? 

The local shop that I use has an engine from a '95 S320 (with 112,000 miles) for $1200. He will do the labor of the engine swap, accessory change, and replace all of the major seals for another $1200. So that would be $2400 for the engine swap including labor. While I have the engine pulled, I will change all of the hoses and hard to reach items at the same time.

It would probably be a good time to rebuild the seals for the steering as well since I can easily get to it.

What do you all think? For the cost of the replacement head and labor, I can get the whole engine... 

Jono doesn't hang at most of the pedestrian forums anymore (Banzworld, PeachParts) because the folks at Benzworld W126 turned on him (like they have with many knowledgeable folks over the years, who just end up leaving and going elsewhere) and for lack of time. The guy is BUSY.

I only know of Steve by reputation but it's dang good. Either guy as well as Europa Auto is going to have good machine-shop contacts who are competent to do the job. When I had my own M117 and M104 heads done, I asked around to find out who all of the best indy shops and dealerships here in Houston go to. It came back almost unanimously that the go-go machine shop for Benz motors in Houston is Scroggins Machine.

I'm sure that most every medium or large city has at least one "go to" machine shop for Benzes. When I lived in Portland, Oregon it was Bearing Service Company, located on the edge of the Pearl District downtown.

Cheers, Gerry

I have not yet pulled the trigger on swapping the engine yet. Has anyone here swapped their M104.996 with an engine from the sedans? I already know many of the parts on the engine are different, and will have to be swapped out, For example, the water pump is different, and will need to be swapped with new gaskets.

Will I be able to re-use any of the bolt-on parts that will come with the replacement engine that has less miles? Fuel Rail, Sensors, Intake Manifold, or am I only going to replace the block and head? I would like to take advantage of as many parts as possible from an engine that has less than 100K miles.

I also have no idea what the differences are between '95 / '96 / '97 / '98 engines from the sedans and how they will compare with mine.

Now I need help finding finding a good 3.6L AMG engine. So far I've had no luck finding one...

The M104 changed in a lot of ways from the model year 1996, when it went into the W210 models. You'd be better off using one from a 1993-1995 W124 model as a base.

Are you intending to retain your existing transmission? My reason for asking is that there were two versions of the 3.6L AMG M104 engine. The earlier versions used the near-identical 722.3 four-speed automatic transmission as the G320, while the later 3.6L motors used the five-speed 722.6 automatics.

So if you got your hands on a later 3.6L motor, you'd also have to swap the transmission and all associated electronics, because it doesn't use the same HFM engine management system that the earlier sedans/wagons, and the G320, do.

I also have begun researching the transplant of a C36 AMG motor into my own G320, and I already have a line on a used 3.6L "early" engine that the seller will be removing from his 1995 E320 wagon mid-year. I plan to put it on an engine stand in my shop and do the external build-up from there.

Right now, via the EPC, I'm doing a detailed, system-by-system comparison of the M104.992 and the M104.996 and creating a spreadsheet to determine all of the parts I need to procure to do the switchover. I plan to obtain a G36 AMG HFM computer over the summer on my annual trip to Germany.

The swap will probably happen next winter, if things go according to plan. Definitely interested to hear your findings, and perhaps we should compare notes going forward. Sounds like you are farther along than I am, though.

I'm pulling the trigger on swapping this engine, although have not been able to find an AMG engine with less than 160,000 miles on it (of finding an entire car as a donor).

As an FYI, I am planning on re-using my transmission. It's a factory re-built with only 25,000 miles on it.