One of the nice virtues about M5 ownership is meeting people. Throughout the 10+ years that I own and drive my E34 M5 and E28 M5, I have met hundreds of similar minded petrol heads like member RobertK, who owns one of the very last European E34 M5 3.6litre models that was manufactured in December 1991 and first registered in spring 1992. Another advantage of seeing all the cars and their owners is the knowledge that can be gathered by listening and analyzing the owner-experiences and if necessary use them to your own advantage.
As said, GD55450 was first registered in Holland at the end of May 1992. This is unusual for a HD91 model as the early HC91 models were already readily available. In the 18 years that has passed, GD55450 racked up the respectable mileage of roughly 280000km (verifiable). The car has aged well for its eighteen-years, most of them as everyday transport. Its current owner obtained ownership of GD55450 in spring 2004 and since then invested a lot in maintenance, repairs and TLC. He has experienced the questions, challenges and virtues of E34S M5 ownership just as any long-term owner.
Robert saw me and some others doing more and more by ourselves, with as highlight the engine rebuild of my E28 M5 (click here), its reinstallation (click here) and the recommissioning (click here). Throughout the years, I have helped him to solve many issues, some as a consultant and some actively by helping him doing the work with Robert being the assistant.
One of the main issues of last year was the oil leakage on the exhaust. In spring 2009, we diagnosed a leaking gearbox shaft seal and a leaking gearbox-gearshift seal. We also noticed that the sump-gasket was leaking small amounts of oil as well, but as the latter was a minor issue it was decided to leave it at that and only solve the gearbox leaks and replace the propeller-shaft center bearing that had seen just enough after 275k km’s. Next to that, we replaced the gearbox shift mechanism and all of the exhaust mounts. The condition of the center bearing surprised us as the enclosure had developed an oval-shape. This probably is the result of deteriorating rubber that allowed a larger swing of the bearing inside its enclosure. Under high load, this causes a large swing of the propeller shaft as well. For some time, the enclosure limits the swing, but the forces that it has to endure will eventually cause it to break. Believe me, you don't want that from happening.
With the new center bearing and gear-shift mechanism, Robert reported that the drivetrain vibration that he couldn't pin point before, disappeared completely and that the gear-shift improved as well.
Soon after, GD55450 started to develop another oil leak, which turned out to be a leaking seal between the camshaft house and the rear-cover, as well a leaking oil return pipe. The required corrective measures were rather simple and were solved by a Dutch BMW specialist. For a long time, GD55450 remained stable and Robert fully enjoyed driving her. However, he did report some running issues after which I suggested to carry out the basic throttle body synchronization.
When we removed the intake plenum and the enclosure for the air filter, I smelled some gas that quickly turned out to be a leaking fuel hose in the engine compartment. After removal of the supply and return hoses, we discovered that one of the three hoses had been replaced before with a multi-purpose fuel hose from Gates. Needless to say that it was this part failed.
After cutting the damaged section, it quickly became apparent why the hose from Gates failed. Just take a look at the reinforcements in the mold from the hose.
As it turned out, the hose from Gates was replaced shortly after Robert took ownership of GD55450 in April 2004, and thus this hose is just six years old. For comparison, the hose with the thick reinforcements is an original BMW fuel hose and is eighteen years old. Despite that the BMW fuel hose has hair-line cracks on the inside of the molding the reinforcement of the OE-hose is strong enough to maintain the structural strength of the hose whereas the Gates hose was not able to withstand the high pressure in the fuel hose. Since I always carry some OE-quality fuel hose on my cross continental trips, I had just enough stock to replace all the hoses in the engine bay to solve the problem.
Another issue that came out of the inspection was a slight coolant leak between the upper radiator hose and the overflow pipe coming from the cylinder head. Originally, the S38B36 and S38B38 have a plastic extension pipe between the cylinder head and the upper radiator hose. The problem is that these plastic pipes become brittle over time and when the upper radiator hose needs replacement, it cannot be removed on one piece. At that point, the correct replacement part is often not at hand and the mechanic decides for a work around. He probably cut a small section from the original extension pipe to create an interconnecting piece to an intermediate overflow hose, but why does that have to be a fuel hose, probably of the same inferior quality as the failing fuel hose?
This is a serious point that needs to be resolved ASAP as you don’t want this leak to develop into a disconnect! Unfortunately, this part was not at hand so we could not proceed with the corrective measure. Next to this issue, we discovered that the oil return-pipe was leaking again.
This was rather a surprise as it was replaced a few months before so it appears as if the BMW specialist did not use the correct procedure. Anyhow, the corrective measure required new parts that were not at hand at the time so we carried on with the calibration and adjustment of the throttle body synchronization. The calibration revealed a difference between the idle-setting of the three pairs and an incorrect full throttle setting. As these were never adjusted in the past, this was expected. The corrective measure was the removal of the individual parts for a full clean and adjustment of the throttle body synchronization.
More compelling were the valve-clearances. Since these were adjusted by a main dealer not that long ago, we expected them to be within specification, but strange to our surprise, my 0,30mm feeler gauge didn’t fit ten out of twelve of the exhaust valves and I needed the revert to the smaller 0,25mm feeler gauge to do so. Since some resistance could still be felt, I could only conclude that the clearances of the affected valve are at least 0,03mm too narrow. Either way, the main dealer did not adjust the valve or did not adjust the valves properly.
The throttle body synchronization changed GD55450’s throttle response significantly. It does not cough at idle anymore and is much stronger in the mid-range in every gear. Despite that, I suggested to have the injectors ASNU tested and overhauled by Prickartz consult in Linnich (Germany), the company who successfully overhauled the injectors for my E28 M5 in February 2010. This improved the mid-range and full-throttle even further and Robert was very satisfied whereas I was amazed that an S38B36 with that mileage still runs so strong.
Even though we later resolved the leak alongside the oil-return hose and Robert corrected the poor quality coolant overflow hose, Robert still complained about oil leaks. As I already had a theory, I instructed Robert to diagnose this by himself, which he did soon after and concluded that the oil-leaks were coming from the bell housing of the clutch. Based on the outcome of this test, we defined another project to replace the prise-shaft seal, rear crankshaft seal, clutch, pressure group and clutch release bearing.
To be continued!
As said, GD55450 was first registered in Holland at the end of May 1992. This is unusual for a HD91 model as the early HC91 models were already readily available. In the 18 years that has passed, GD55450 racked up the respectable mileage of roughly 280000km (verifiable). The car has aged well for its eighteen-years, most of them as everyday transport. Its current owner obtained ownership of GD55450 in spring 2004 and since then invested a lot in maintenance, repairs and TLC. He has experienced the questions, challenges and virtues of E34S M5 ownership just as any long-term owner.
Robert saw me and some others doing more and more by ourselves, with as highlight the engine rebuild of my E28 M5 (click here), its reinstallation (click here) and the recommissioning (click here). Throughout the years, I have helped him to solve many issues, some as a consultant and some actively by helping him doing the work with Robert being the assistant.
One of the main issues of last year was the oil leakage on the exhaust. In spring 2009, we diagnosed a leaking gearbox shaft seal and a leaking gearbox-gearshift seal. We also noticed that the sump-gasket was leaking small amounts of oil as well, but as the latter was a minor issue it was decided to leave it at that and only solve the gearbox leaks and replace the propeller-shaft center bearing that had seen just enough after 275k km’s. Next to that, we replaced the gearbox shift mechanism and all of the exhaust mounts. The condition of the center bearing surprised us as the enclosure had developed an oval-shape. This probably is the result of deteriorating rubber that allowed a larger swing of the bearing inside its enclosure. Under high load, this causes a large swing of the propeller shaft as well. For some time, the enclosure limits the swing, but the forces that it has to endure will eventually cause it to break. Believe me, you don't want that from happening.
With the new center bearing and gear-shift mechanism, Robert reported that the drivetrain vibration that he couldn't pin point before, disappeared completely and that the gear-shift improved as well.
Soon after, GD55450 started to develop another oil leak, which turned out to be a leaking seal between the camshaft house and the rear-cover, as well a leaking oil return pipe. The required corrective measures were rather simple and were solved by a Dutch BMW specialist. For a long time, GD55450 remained stable and Robert fully enjoyed driving her. However, he did report some running issues after which I suggested to carry out the basic throttle body synchronization.
When we removed the intake plenum and the enclosure for the air filter, I smelled some gas that quickly turned out to be a leaking fuel hose in the engine compartment. After removal of the supply and return hoses, we discovered that one of the three hoses had been replaced before with a multi-purpose fuel hose from Gates. Needless to say that it was this part failed.
After cutting the damaged section, it quickly became apparent why the hose from Gates failed. Just take a look at the reinforcements in the mold from the hose.
As it turned out, the hose from Gates was replaced shortly after Robert took ownership of GD55450 in April 2004, and thus this hose is just six years old. For comparison, the hose with the thick reinforcements is an original BMW fuel hose and is eighteen years old. Despite that the BMW fuel hose has hair-line cracks on the inside of the molding the reinforcement of the OE-hose is strong enough to maintain the structural strength of the hose whereas the Gates hose was not able to withstand the high pressure in the fuel hose. Since I always carry some OE-quality fuel hose on my cross continental trips, I had just enough stock to replace all the hoses in the engine bay to solve the problem.
Another issue that came out of the inspection was a slight coolant leak between the upper radiator hose and the overflow pipe coming from the cylinder head. Originally, the S38B36 and S38B38 have a plastic extension pipe between the cylinder head and the upper radiator hose. The problem is that these plastic pipes become brittle over time and when the upper radiator hose needs replacement, it cannot be removed on one piece. At that point, the correct replacement part is often not at hand and the mechanic decides for a work around. He probably cut a small section from the original extension pipe to create an interconnecting piece to an intermediate overflow hose, but why does that have to be a fuel hose, probably of the same inferior quality as the failing fuel hose?
This is a serious point that needs to be resolved ASAP as you don’t want this leak to develop into a disconnect! Unfortunately, this part was not at hand so we could not proceed with the corrective measure. Next to this issue, we discovered that the oil return-pipe was leaking again.
This was rather a surprise as it was replaced a few months before so it appears as if the BMW specialist did not use the correct procedure. Anyhow, the corrective measure required new parts that were not at hand at the time so we carried on with the calibration and adjustment of the throttle body synchronization. The calibration revealed a difference between the idle-setting of the three pairs and an incorrect full throttle setting. As these were never adjusted in the past, this was expected. The corrective measure was the removal of the individual parts for a full clean and adjustment of the throttle body synchronization.
More compelling were the valve-clearances. Since these were adjusted by a main dealer not that long ago, we expected them to be within specification, but strange to our surprise, my 0,30mm feeler gauge didn’t fit ten out of twelve of the exhaust valves and I needed the revert to the smaller 0,25mm feeler gauge to do so. Since some resistance could still be felt, I could only conclude that the clearances of the affected valve are at least 0,03mm too narrow. Either way, the main dealer did not adjust the valve or did not adjust the valves properly.
The throttle body synchronization changed GD55450’s throttle response significantly. It does not cough at idle anymore and is much stronger in the mid-range in every gear. Despite that, I suggested to have the injectors ASNU tested and overhauled by Prickartz consult in Linnich (Germany), the company who successfully overhauled the injectors for my E28 M5 in February 2010. This improved the mid-range and full-throttle even further and Robert was very satisfied whereas I was amazed that an S38B36 with that mileage still runs so strong.
Even though we later resolved the leak alongside the oil-return hose and Robert corrected the poor quality coolant overflow hose, Robert still complained about oil leaks. As I already had a theory, I instructed Robert to diagnose this by himself, which he did soon after and concluded that the oil-leaks were coming from the bell housing of the clutch. Based on the outcome of this test, we defined another project to replace the prise-shaft seal, rear crankshaft seal, clutch, pressure group and clutch release bearing.
To be continued!