EDIT Overfueling/Gas and Oil leak exhaust header 1

[fw66]

Hello All!

Post Update: after a lot of research and troubleshooting, it looks like my engine is over fueling. I have spark, I have compression, I have fuel pressure coming out of the injectors (tested all these things). The bike will start when the spark plugs are left out of the engine for a day or so. After that however, the bike remains very difficult to start.

I've been riding my custom k75 for over 2 years now with no real issues but lately it's been rough idling and popping at low RPM. I initially thought it was bad spark plugs so I changed out the spark plugs and everything worked real well for a day or so, low idle RPM was smooth and the bike torqued really well.

After a few days however, the bike went back to rough idle and bumpy acceleration/popping at low rpm. I began to inspect the bike and noticed there was an oil/gas leak coming from exhaust header 1. The spark plug 1 was also quite wet when I replaced it the first time around.

I removed the head cover and a lot of oil drained out. I haven't done any engine work on the bike as all my custom pieces have been non-engine related. Any direction would be appreciated!


spark plug removal, oily.jpg (60.41 kB . 432x576 - viewed 720 times)

exhaust header 1 leak.jpg (61.02 kB . 768x576 - viewed 730 times)

cylinder head removal oil.jpg (45.75 kB . 768x576 - viewed 664 times)

final removal.jpg (59.27 kB . 768x576 - viewed 685 times)

[Laitch]

Welcome fw66! Thanks for the photos.

Usually, when either of the engine covers is removed, some oil will drain out. Buy some sealant like Permatex Ultra Black or Drei Bond (Three Bond) 1209. Either purchase a new cover gasket or clean the oil from your old one thoroughly. Scrupulously follow the gasket mounting instructions in the BMW service manual downloadable from this site, or watch Chris Harris's YouTube video describing valve clearance adjustment of 2V Bricks. When you are ready to mount the gasket, the mating surfaces of the head, cam cover and gasket must be completely free of oil.

After the task is concluded, I advise doing a compression test on the engine when its warm. That will help determine if there could be leaks from valve stem seals, rings or the head gasket. A leak-down test after the compression test will differentiate between those sources. If your preference is just to move on because both the leak and the rough engine performance is stopped by the gasket restoration, I can't blame you. Magical thinking is a beautiful state of being, while it lasts. 

Overfilling of the crankcase with oil could also be part of this problem so pay attention to the oil level in the sight glass and don't fill it all the way to the very top of the ring. I check the oil after the engine has been run then shut off for a few minutes. I want to see the oil level somewhere above the middle dot and just below the top of the ring.

Lurking out in your future are the thorns among the roses—a propane test of the crankcase z-tube and the throttle body rubber manifolds for leaks, inspection of the throttle body vacuum port caps for integrity, a cleaning of the air filter, followed by a valve clearance adjustment, a throttle body balance and a CO adjustment. 

[fw66]

Thanks for the response Laitch!

So bad news...got the gasket cleaned and replaced, everything is free of oil and used permatex bond in the 4 corners. Started the engine back up, very rough idle once again and then the engine died after about 3 minutes of running.

From this point on, the bike wouldn't start again. I don't have the tools immediately available for a compression test but I'll get my hands on one this week.

Any ideas?

[Laitch]

All I was doing was helping you fix an oil leak. Did it quit leaking? If it did, that's good news not bad news. Is the #1 plug still oily?

Tools and gauges can be borrowed from most of the major parts houses for only a deposit on them—no fee for use.

[The Mighty Gryphon]

In the photo of your old spark plugs the terminals on two of them look very corroded.  I would suggest that you get some electronics cleaner(Deoxit D5 is preferred) and shoot some into the plug connectors on the plug wires and work them on and off of the spark plugs to clean up the connection.  Did you replace them with NGK D7EA's?  Those plugs do not have terminal nuts, and as a result do not have the best electrical connection.  You will need to get a set of nuts for them.  Usually a small engine repair shop will have a bucket of old spark plugs that you can take the nuts from to install on your new plugs.

Have you checked the breather hose from the crankcase to the air box above the throttle bodies.  It is located at the rear of the air box behind the throttle position switch.  Remove it to look at it closely.  They have a habit of cracking where they are clamped and creating air leaks that mess up the fuel air mixture when starting and at idle.  You need to flex the hose a little to see the cracks.  If you see even one crack, get a new hose.  For testing purposes you can carefully wrap it with electrical tape to see if it improves the running of the engine.

You could also have air leaks around the throttle bodies.  You can look into that possibility after confirming the breather hose is okay.

[rbm]

Good advice from Laitch and TMG.  In addition, I'd take a look at the exhaust, especially the copper gaskets that seal the exhaust header to the block and at the joint between the exhaust header and the muffler.  Air leakage in that area will lead to popping, especially on the overrun.

[fw66]

Thanks for the responses.

@Laitch, so far there hasn't been any additional oil leaks but the bike didn't run for very long after the gasket service before the engine stopped running. I'll have a better idea when I get the engine started again

@TMG, I replaced the breather hose about 2 years ago as I did noticed it was cracked. The new one looks fine so I don't think this is the cause. I'll use some electrical contact cleaner and clean up the plug connectors as they are quite corroded. The sparks I replaced them with were Bosch X5DC plugs, not the NGK's.

@rbm, I'll take a look at that as well, right now my biggest problem is the engine not starting!

Stay tuned for comp test and leak down test results!

[Martin]

After cranking it over and it fails to start remove the spark plugs and check to see whether they are wet or dry.
Regards Martin.

[Laitch]

If cleaning the plug wires doesn't get it, you'll need to check the grounds—the frame ground under the tank in particular if you've had the frame painted. Be sure all the ground cables are connected to bare metal. After that, clean the ignition switch connector down there too, and verify that all connector a tightly fastened. Then verify that the coil connectors are clean on both primary and secondary wires and secondary sockets.

[fw66]

Didn't get a chance to do a compression test today but I did check some things off the list:

- The bike is turning over, the engine is just not starting. Sometimes when I open the throttle I hear a few pops but that's it
- I checked the fuel injection and I have good fuel pressure and consistent/same jetting on all three jets
- I do have spark, which should mean ignition coils are all grounded and working correctly

@Martin, the plug is usually wet after cranking and I do have spark on the plug as well, perhaps an air inflow issue?

[daveson]

OK another long shot but a quick check. Let the bike idle for a bit then turn it off. Remove the fuel pressure regulator vacuum hose from throttle body three. If there are any signs of fuel or moisture in the hose or it's barb, or a fuel stain from the barb, the regulator diaphragm is leaking, allowing excessive fuel into the engine.

[Laitch]

Didn't get a chance to do a compression test today but I did check some things off the list:

If the engine isn't over-fueling from conditions that daveson described you'll need to commence cleaning and checking the frame ground connections under the tank for tightness to bare, unpainted metal. After that, inspect, clean, and check for tightness the electronic control plug under the tank,  the ignition switch connector under the tank, the battery ground strap connection on the transmission; the battery post connections, the Jetronic plug connection under the seat and the starter wiring connections and its bolts. All of these have potential to interfere with starting the engine.

Many of us use DeoxIT D5 because its deoxidation and protection properties have proven effective. Look for it at a music store that stocks electronic equipment or at auto parts stores.

[Martin]

After trying to start and failing, remove the fuel pump fuse No 6 marked Kraftstoppe and try again. If it tries to run but stops it's due to lack of fuel. You then need to test the temperature sensor switch values. A faulty switch will cause it to over fuel and by removing the fuse you are allowing the engine to burn off any unburnt fuel in the combustion chamber.
Regards Martin.

[fw66]

Got some updates, did a compression test and things looked pretty good:
- 170, 160, 170 on the 3 cylinders

I added a fresh few liters of gas to the tank and tried running the bike again and still the engine won't start.
I removed fuse number 6 and ran it again and same thing, no difference.

Would you suggest I look into getting a new temperature sensor?

I'm wondering if I need to remove the spark plugs for a while to let the engine air out any over fueling (not sure if there is a better way to do this)? It seems that this could be the issue right now.

[rbm]

It's a gasoline powered engine.  It needs spark, fuel and air.  Are you getting spark?  Is there fuel getting into the cylinders?  Does air mix properly with the fuel?  Answer these questions and it may lead you down a path to the problem.

Martin's method will tell you if you are getting gasoline in the cylinders or not.  It will tell you if you are getting too much or too little.

What about the injectors?  Are they operating? Is there fuel pressure?  What is that pressure?

Have you checked the ignition system to ensure the plugs are sparking? The condition of the plugs is very suspicious leading one to believe the ignition wires might be problematic as well.  Maybe changing spark plugs and ensuring they are suitable for the bike (caps, resistance, gap) would be prudent.

These bike are victims of poor electrical connections and checking those connections for integrity  and solidity will help eliminate many weird symptoms.

Be systematic in your investigation and try to eliminate as many variables as possible which will eventually lead you to the problem.

[Laitch]

Have you checked everything listed in Post #8? Test the temperature sensor before you buy one.

[fw66]

Got the bike running again!

I left the spark plugs out of the engine for about 2 days to let everything dry up, I started the bike today and it fired up, lots of smoke but it ran well and even was idling well.

Not sure what the issue was, any ideas? Here's what I'm thinking:

1. Rain water got into the gas tank, I was running relatively low on fuel and rode it around for another week and bad water/fuel mixture got into the engine causing things to run very poorly.

2. Over fueling, I haven't gotten around to testing the temp sensor yet but too much fuel flooded the engine and leaving the sparks out allowed things to dry. I'm not sure what else could cause over fueling but just basing it off of what Martin mentioned

Long story short, I think it's possible the leak from the exhaust header wasn't oil. It may have been fuel/water mixture that wasn't combusting? Not entirely sure.
Any thoughts would be appreciated!

[daveson]

It's maybe also time to replace the fuel filter.

[Laitch]

Not sure what the issue was, any ideas?
Any thoughts would be appreciated!
Long story short . . .

My first idea would be for you to quit hypothesizing and enjoy the ride.  You don't know what happened. Leave it at that. 
Secondly, if you want preliminary confirmation that you have an oil leak, touch the leaking fluid with one of your fingers then rub that finger against your thumb. If the resulting sensation is oily, oil might have something to do with it.
Post some profile photos of your moto. The fuel tank and the cap assembly is designed to divert rainwater from entering the tank. If you had old fuel within the tank, condensation might have diluted the fuel or the fuel separated.

Finally, you've made a short story long but you have prevailed anyway. Ride on!

[fw66]

So the bike started a few days ago and I didn't get a chance to ride it until today. Of course upon starting the bike, the same problem persisted.

It seems that I may have an over fueling issue as leaving the spark plugs out of the engine helped start the bike up again.

I've read quite a lot of forum posts regarding over fueling by now and am suspicious of a few things:
1. Temperature sensor, I'm going to test this for correct values next
2. Possible injector leak? I pulled the whole rail out to inspect fuel pressure in my diagnostics a while back and didn't notice excessive leaking on any of the jets, is there a better way to confirm this?
3. Bad ECU? I know it's pretty rare for these to fail but I read in some forums that replacing this has fixed the problem. Would this be an issue if the jets weren't leaking?

Lastly, I remember when testing the jets for spray, I removed a fuel line with the bike completely turned off and a bunch of fuel was still coming down from the nozzle at the tank.
I'm not sure if this is supposed to happen, could this mean that my fuel pump is faulty?

[Laitch]

Did you clean and check everything as indicated in Post #8? If you haven't, I suggest you quit hypothesizing about the cause and undertake an orderly search for the cause once you have performed the tasks in Post #8. There is a link to a No-Start troubleshooting guide at the end of this post.

[fw66]

Hey Laitch,

Thanks for the reminder about checking all electrical connections. I took the time today to remove the tank and check all my connections and here was what I checked:

I cleaned the grounds to the frame and it didn't look like that was the source of the problem.
The connector under the tank was working as expected, no rust looked good.
I pulled the plug off the EFI and connectors look clean, no corrosion.

I suppose based on Johny's post, I haven't cleaned the starter in the fashion that he had mentioned before. I'm not entirely sure if this is looking like a starter issue though because the bike does turn over/crank well.

Any thoughts on where to go next? I read the PDF and perhaps will have to start getting into testing electronics.

I did notice that the temperature sensor had a bit of corrosion around the outside of the body, perhaps it could be causing overfueling?

[Laitch]

Did you inspect the air filter? A clogged air filter can result in an over-rich fuel mixture.

You still haven't checked the coil wire terminal connections mentioned in Post #8. The terminal sockets can erode then interfere with ignition. In addition, you should check coil resistance.

You're fixated on the coolant temperature sensor. You should probably get that fixation out of your system. It can be tested electronically or by removal using the boiled water test; both tests are in the troubleshooting guide. I suggest you do both tests; that should cure you. 

You've got plenty of fun ahead—fuel pressure testing, injector coil pulsation, air flow meter vane ease-of movement. Just remember, when you ask a question that starts with "Could it be . . .," you may as well consider "Yes" as the answer.

[riots100]

If you have spark, fuel, compression and air, then you might look over my past K75 adventure.

http://www.motobrick.com/index.php?topic=7661.msg57782#msg57782

There are similarities and solutions to be noted.

[fw66]

Thanks for the pointers.

I took the coils off today and cleaned/inspected them- connections look secure and aren't corroded. I have an ohm meter but am not quite sure what to test for since the PDF guide is for the k100 coils.
Are the values and testing method the same for the 3 coils on the K75?

Furthermore, it's more unlikely that the coils are damaged if I have confirmed that I have spark on ignition for all three spark plugs right? Or is there something I'm missing here?

Some things I am going to be getting to:
- Testing fuel pressure for exact pressure numbers. I skipped this part because I pulled the injectors and checked for spray pattern/leakage and it looked good, vacuum tube to throttle body 3 was also not leaking or smelt like gas. I'll have to confirm fuel pressure once I put the bike back together.
- Test/replace temperature sensor, the sensor has a blue-ish hue on the nut which doesn't look like it's in the best shape, not sure if this would be the exact cause.
- Doing more research on the hall effect sensors? I've read this is a possibility...