With the manual swap essentially complete, I now turned my attention to maintenance items and refreshing the engine. There were lots of items that I wanted to take care of. The engine needed a refresh of all of the hoses and plastic parts. Most of the parts were either original or missing. I am very particular when refreshing things and am always keen to replace a wear item. This was going to be a learning experience and looking back I am glad I did this because it allowed me to learn the M20 2.5L engine intimately.
I installed the refurbished driveshaft in the car. The refurbished Ireland Engineering driveshaft went in without any drama. In the final step to get the car running, I needed an exhaust. I did a lot of research and found the Ireland Engineering cat-back exhaust to be a great option and deal. Another plus was I got and I got to support a local shop in Southern California. I also got a new muffler strap kit since the last muffler was a custom install and the straps were missing. Now that the cat-back was installed I needed the section of the exhaust that went from the headers to the cat-back which included the catalytic converter. A quick Facebook marketplace search found a partial exhaust and a cat for the e30. A quick drive and deal later, I had all the parts to get the car running. I then took the car to ARCE Mufflers where he welded the exhaust from the headers to the cat-back. This signified the completion of the manual swap.
I spent a few months driving the car around. It was truly a blast to drive. All of the hype about this car is true. It hugged the turns and it was hard to get the smile off my face. Although not fast, I loved rowing through the gears. One disappointing thing about the manual swap was the fact that going from 1st to 2nd was almost impossible. The synchro was shot. This is always a possibility when buying used car parts secondhand. Fortunately, with the differential gearing of 4.10, 1st gear was essentially useless. I ended up only using 2nd to 5th. The only issue was the car was essentially driving at 70 mph at 3,000 to 3,500 rpm. This could be corrected by adjusting the rear differential to a 3.73 ratio. All in all, the manual swap went well. A few complaints about the transmission but that can be corrected at a later date.
I now could shift my attention to refreshing the engine bay. I started with a few simple items first. I replaced the ground strap that goes from the body to the hood. A couple of screws and the job was done. The next task I completed was replacing the coolant reservoir sensor and connector. The level sensor was easy enough to replace but I had to do a deep Google search to find a replacement for the connector. The part number ended up being 61-13-1-378-408. I then had the genius idea of pulling off the intake manifold and replacing all of the 30-year-old parts. This of course was the only logical thing to do since I had just gotten the car running.
After removing the intake manifold from the engine, I came across a video of how to clean the inside and out of your intake manifold fully. This video recommends using dryer vent brushes to clean the inner runners. In the video, they recommended using Purple Power degreaser but of course, I wanted to be smarter and decided to use KBS Klean. A few people on some forums recommended this for aluminum. They, however, neglected to mention that the KBS Klean needed to be rinsed off immediately after the cleaning process. I did not follow this step and let the manifold soak overnight. When I awoke to check on the intake manifold in the morning, I realized the aluminum had started to corrode.
Aluminum does not rust but it does corrode. The manifold started to develop oxidized areas. This was over the entire manifold, both inside and out. I was able to wipe off a lot of the oxidized white power but I soon realized I could not get to the inside of the manifold. I soon knew I would have to use a less powerful degreaser and not have the part soak overnight. I fortunately had an extra manifold from the spare engine I had purchased. This time, I would use Purple Power degreaser and not let the manifold soak overnight.
The results were night and day. The aluminum was not darker and no oxidation appeared this time. The dryer vent brushes worked wonders and I recommend this process to anyone who wants to clean their manifolds themselves. I spent an enormous amount of time scrubbing and scrubbing the manifold to get 30 years of dirt and grime off the manifold. This was an OCD labor of love but the results were amazing. I learned a valuable lesson with aluminum along the way. Sometimes experience is the best teacher and lesson learned.
The next project for the manifold was the thermostat housing. I picked up a thermostat housing from Ireland Engineering but there was something I wanted to do to it before I put it back on the car. On E30’s there is a coolant that passes through the throttle body. The coolant passes from an opening in the back of the block and through some hoses, circulates through the throttle body, and then makes its way to the thermostat housing. A common upgrade is to delete the coolant line through the throttle body. This delete is useful since it lowers the air temperature flowing through the throttle body. The purpose of the warm coolant in the throttle body in the first place is to prevent the throttle body from getting frozen over in colder climates. Since I live in Southern California, I will never have this issue. The first step was to remove the nipple line on the thermostat housing and tap the hole and plug it with a screw. I used a 12mmx1.5 tap to make the hole in the thermostat. I then purchased a plug for this hole and the job was done. I put in a new thermostat and replaced the two sensors and installed the housing on the engine.
The next part of refreshing the manifold was replacing the vacuum lines that travel to the brake booster. I purchased new vacuum lines and a stainless steel hose clamp kit. I cleaned up the plastic parts that tie into the intake boot and brake booster with the ultrasonic cleaner. A fairly simple repair that was made easy because I was able to mimic the old lines. This was peace of mind for eliminating vacuum leaks.
The second part of the throttle body coolant block off was eliminating the hose intake and outlet. There is a special aftermarket part that eliminates the hose barbs. I bought mine off of SSQuid for $20. The part is called “M20 Throttle body Coolant Block Off”. No gasket is needed. Just use the screws used for the original part with the hose barbs. My throttle body also had some loose vacuum barbs. I mixed up some JB Weld to fully seal the barbs. This was also good insurance to eliminate any of those pesky vacuum leaks.
I also decided to upgrade the injectors on the M20 engine. The injectors I pulled off the car were a Ford model and I think they were 19 lb injectors. I spent a long time on the forums learning about injectors and a good compromise of performance and fuel economy was using a 17 lb per hour injector. A quick search led me to Injector Planet. I ended up buying the Bosch 0280150415 / BMW 13641730060. They had great prices for remanufactured injectors. I cleaned the fuel rail and popped the injectors in on the manifold. The last part of the throttle body coolant bypass is installing the plug in the back of the block of the engine. This was a M14x1.5 plug.
Another part of the cooling system that was a weak point and part of a recall, was the heater core coolant bypass valve. When these cars were new, the heater cores were consistently popping due to high pressures. The solution was to install a bypass valve with some new hoses to prevent the damage. The car had the repair done but it looked like it had never been touched. I was replacing all of the hoses so I decided I would tackle this too while I was in there.
I was glad I decided to replace the heater core bypass valve and hoses because the valve was severely deteriorated. The valve appeared to be blocked with corrosion and the hose barbs were corroded too and were barely allowing a secure connection to the hoses. Remarkably you can still buy the recall part and all the hoses for it. This was a project I was glad I had done. There would have been no way to tell if this part was functioning because the heater was still working.
I was adamant I was going to tidy up the engine bay just as it had been right out of the factory. It is kinda OCD but if I was going to spend all this time I might as well do it right. There was one little clip that I had trouble finding. The clip was for holding the wire harness under the manifold. I had to ask the forum for help. Sure enough, the small clip was part number 16131177583. The coolant pipe was showing signs of corrosion so I decided to give it another coat of paint to clean up the engine bay.
After fully assembling the throttle body and all of the vacuum lines, the intake manifold was ready to return to the car. One thing I also decided to take care of was new rubber fuel lines. I replaced the lines that go to the fuel regulator and the fuel lines that go to and from the charcoal fuel canister. With everything refreshed, it was time to put the intake manifold back in the car. Installation can be difficult because there is a tube that goes from the oil pan to the bottom of the intake manifold. It’s spring-loaded and a pain to get on when installing the manifold. The best way to deal with it is to compress the spring with a zip-tie, install the pipe with the spring, and then cut the zip-tie when everything is in place to release the spring. Eventually, the manifold relented and I bolted it all in. I hooked up all the coolant hoses and vacuum lines and reinstalled the intake. Next up would be updating the oil cooler and radiator. Motor on.