The UK C1 Forum - Not logged in
Morning gents. My first posting, I hope this makes some sense.
I have a 2001 125 exec , it has been SORN for over a year and now it needs to go....It was laid up due to too tight valve clearances , so did not want to burn the valves. These have now been sorted and the bike started on the button.
My problem now is that there is a metallic cracking noise coming from the rad cap area , combined with the expansion tank "puffing up" at the same time.
When removed the rad cap , a load of coolant rushed into the expansion tank ......
I have changed the thermostat as the larger rubber hose facing to the front was not getting hot and that now seems to be working. The temperature warning light does not come on but when i try to start it there is a bubbling sound from the expansion tank. i have not completely drained the system , but i have bled the system as per the manual ie cap off , open the bleed screw by the chain tensioner until no air comes out , and refill to the bottom of the neck, but still it continues to drain into the expansion tank (the rad cap is new too) and i have to drain some out. If i open the bleed screw some air does come out. I have replaced the oil and filter after the valve buckets were replaced , and there is no change in oil level or signs of water contamination.
I am obviously missing something here, and i hope that some one can help me ....
Kind regards kmac
Possibly head gasket? If it’s leaking from the cylinder into the coolant system the compression will push air into the coolant. A compression test could help diagnosis.
Smells head gasket issue.
Temp light will eventually turn on after some more wear.
Bubbles while the engine works possibly means that combustion gases leak to the coolant circuit.
You can test compression with a tester but the surefire thing is to open head and look.
There is a poor's man solution to pour a "seal-a-gasket" treatment and hopefully save it.
I haven't tried it so I don't recommend.
As Alunt says, sounds like possible head gasket gone —-due to overheating after the thermostat failed???
How exactly is the expansion tank “puffing up”? The lid is only loosely held on (the one behind the seat back-yes?)
Who did the valve clearances?
Oh—and does the hot warning light come on with ignition? Does it light up at a all?
Hi all , thanks for your replies.
I suspected head gasket , but there is no smoke from the exhaust, the oil is not contaminated and level correct. Is there another coolant valve or bleed point somewhere that i am not aware of? When turning the engine over it is not whizzing quickly. The coolant light does come on with ignition and self checks. I have taken the plug out and there is no coolant smell (just fuel , because it wont start)
The expansion tank puffs up in time with the metallic click from the rad area (like a lung working - approx once every 30 secs.
Have i bled it properly, is there a more foolproof way of doing it.
If it is headgasket, what sort of job is that as my mechanical skills are ok ( i did the valve clearances , and they are now spot on)
Again, thanks for your time and help .
Try a Gunsons compression tester with suitable adapter for the spark plug size. If the head gasket is leaking it will soon let you know. Compression needs to be at least 11 bar, preferably 12 plus when turning the engine over on the starter with a good battery. If your engine is turning over slowly you may need a refurbished starter motor or better battery before you can get a proper compression reading.
Thanks for your replies, seems like the head gasket it is then. Will locate a compression tester and update once i have tested . When i stated the engine is not whizzing over, i meant that it is turning over normally , not like it has no compression at all (just to clarify).
Do i go genuine with the parts or can someone advise the best place to get the kit, and can it be done in situ or engine out ? is there anything else i should look out for?
I get head gaskets from BMW, I've not found an alternative. Make sure you order one for the right engine size.
It's an engine out job as far as I'm concerned. Getting it out isn't such a huge job as long as you don't come up against corroded exhaust nuts or similar types of hurdles. Once out all jobs on it are so much easier.
You'll need a torque wrench and a way of tightening the head nuts, which are difficult to access. For the inside ones I use a small socket set of decent quality, which will stand the torque. For the external ones I use a swivel headed double ended ring spanner of decent quality, and attach the torque wrench to that when it's 90 degrees to the nut.
Thanks. will price it accordingly. The exhaust will come off easy enough as been off recently. I have torque wrenches etc. My only concern is the condition of the electrical plugs up by the right seat belt catch area (to starter etc, i think)
Anything else to check whilst it is on the bench? What work required to rekit the waterpump ??
Many thanks kmac
Check the valve clearances and adjust if necessary, much easier with the engine out. I recently had a lower cylinder gasket leaking, a cheap part but engine dismantle required to replace it. Piston ring compressor useful for this job. Water pumps do wear out, not a big problem to replace with the engine in the bike.
The timing chain etc were ok when I had the camshafts off to do the valve clearances ( the original fault , ironically) I do have a waterpump kit here ,so will do that at the same time
Thanks Andrew, will let you know how i get on.
It may be good idea of recording video and share YouTube link with us/your bike problem.
Yes, better make a video with the bubbles in the expaksion tank.
Head gasket blown can have several versions of damage. It can be in your case a tiny "hole" that allows only gases to enter the coolant circuit and not (yet) the opposite. It has to do with where exactly the head gasket has been damaged.
Got myself a compression tester and tested the engine twice ( from cold) turned engine over for approx 10 secs. each time. Results were 13 bar and 14 bar respectively. Bizarrely the engine has stopped pumping coolant everywhere but i can still get air out of the bleed screw. How do i know when the coolant is full as when i topped the rad up to bottom of neck (as per workshop manual) refitted the cap and turned it over , it flowed a lot into the expansion tank . i have drained this off and will try again tomorrow. road test seems ok but cuts out at junctions ( restarts on the button , got a new plug in today)
Any ideas ......?
Cutting out at junctions:
Spark plug worn
Battery terminals loose
Idle valve defective (rare)
Intake manifold cracked or loose on head (rare)
Early symptom of burnt valve (rare, usually accompanied with difficult starting)
Confirmed the injector leaking air with brake cleaner, thankyou. I have removed the injector and cleaned the big seal , when refitting ,it does not seem to go right to the bottom (i.e 2mm sticking up over the housing) Is this right, as it does not seem very tight on the injector. I have tried an additional O ring seal on the bottom of the injector seat and refitted , but to no avail.
Also i have noticed that the injector swivels in it's housing when the injector rail is correctly fitted (could not refit the electrical plug, until i worked it out), is this right as well ?
Is there a seal at the top which needs replacing? What seals are available, i read on here that the big seal is not available separately ??
Had a new plug couple of days ago, and always restarts straight away after cutting out. Compression OK and valve clearences spot on.
IS there an easy check for the cooling fan, as I have not heard it come on once whilst I have been trying to sort this out , the fan turns by hand so not seized.
My thanks to you all for your help
Assuming you’ve got the correct sized O ring in now, you can either seal the large ring with sealant or build up layers of a suitable tape on it to help it seat better. I use self amalgamating tape.
I can't comment on the coolant problem but the cutting out at junctions and restarting easily can be a symptom of air getting past the injector. With the engine running, spray some brake cleaner (aerosol) around the injector - if the engine note changes (speeds up) air is getting past the injector. This can mean a new 'O' ring on the injector itself or some sealant to seal the gap between the rubber/metal insert that surrounds the injector in the inlet manifold.
Hope this helps.
Compression sounds ok, so head gasket may be ok as well. If the coolant problem is settling down try running the bike round for a few days and monitor the header tank and sometimes the filler cap level.
Powered by mwForum 2.16.1 © 1999-2008 Markus Wichitill