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Go Back   Madabout Kitcars Forum > Mad Build Area > Marlin Sportster, Cabrio, Berlinetta and Roadster builds

Marlin Sportster, Cabrio, Berlinetta and Roadster builds Enthused or Confused about your vintage Marlin build? Ask away here or show off your build.

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  #1  
Old 27th September 2014, 17:21
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Evening all.

I've now got my exhaust system installed on my M50 and unfortunately, now that I can hear the engine rather than just the roar from the manifold as previously, it sounds, well, just horrible. Take a look at this short vid

https://www.flickr.com/photos/58068042@N07/15370329065/

I'm hoping that this is just down to it only having been run for short (30secs to a minute) bursts over the last year or so to demo the beast to friends etc and needs to be run up to temp to settle down a bit. I've topped up the oil as it was on min but that made no difference. I guess after a warm up test the next steps are:

1. check none of the spark plugs are loose and maybe stick some new ones in anyway.
2. check for misfires. The plugs are the originals and I could unplug each coil one at a time to find an offending cylinder
3. Torque the manifold up a bit more though I'm reluctant to do that and risk stripping the threads on the head.
4. something else? I'm open to suggestions

I'm pretty sure it's not the hydraulic lifters as you can hear the valve train chattering away much more quietly in the background and vanos rattle is usually much less rhythmic. I also think it's way too loud for injector noise. I'm just really hoping it's not a bearing though I think that would be even louder and be pronounced under rev'ing where as this noise seems to settle a bit after rev'ing.

Does anyone have any other suggestions on what the best next course of action is?

thanks
Ian
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  #2  
Old 27th September 2014, 23:10
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Quote:
Originally Posted by morris View Post
Evening all.

I've now got my exhaust system installed on my M50 and unfortunately, now that I can hear the engine rather than just the roar from the manifold as previously, it sounds, well, just horrible. Take a look at this short vid

https://www.flickr.com/photos/58068042@N07/15370329065/

I'm hoping that this is just down to it only having been run for short (30secs to a minute) bursts over the last year or so to demo the beast to friends etc and needs to be run up to temp to settle down a bit. I've topped up the oil as it was on min but that made no difference. I guess after a warm up test the next steps are:

1. check none of the spark plugs are loose and maybe stick some new ones in anyway.
2. check for misfires. The plugs are the originals and I could unplug each coil one at a time to find an offending cylinder
3. Torque the manifold up a bit more though I'm reluctant to do that and risk stripping the threads on the head.
4. something else? I'm open to suggestions

I'm pretty sure it's not the hydraulic lifters as you can hear the valve train chattering away much more quietly in the background and vanos rattle is usually much less rhythmic. I also think it's way too loud for injector noise. I'm just really hoping it's not a bearing though I think that would be even louder and be pronounced under rev'ing where as this noise seems to settle a bit after rev'ing.

Does anyone have any other suggestions on what the best next course of action is?

thanks
Ian
Do nothing! - except run your engine for longer.

Mine did exactly the same: I felt physically sick when I heard mine run for the first time as it sounded so bad.
All you need to do is allow it to run for longer and get up to full temperature - I assume it was the hydraulic tappets which needed filling up, as they had dried out over 5 years of it not running.

Have a listen to mine as it started up for the first time, and compare it to what it sounded like at the end of the evening - and I had done nothing to it, other than let it run for maybe an hour.

https://www.youtube.com/watch?v=61e5GuEgWWE
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Old 28th September 2014, 09:53
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yep the sound your engine was making is almost identical to mine. I'll pop out today and grab 20 litres of petrol and run it for a while. Even when I ran it up to temp a 18 months back when I did my first start it was only running for around 20 minutes and since then it's literally just been turned on and rev'ed a handful of times then off again as the noise was so anti-social.

I need to finish off my centre mounts for the exhaust first then I can drop it back on the ground for more extensive testing
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Old 28th September 2014, 19:58
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You could also try a bottle of this stuff....

http://www.halfords.com/motoring/eng...e-lifter-350ml

...which quietened down even more my already smooth M52
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Old 28th September 2014, 20:32
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I made it out onto the drive today to get the engine up to temp. It did improve but still doesn't sound as smooth as it should. It sounds more like my M54 does for the first 3 seconds after start i.e. a bit of flutter prior to the lifters quietening down, but it just keeps on going. I let the engine come to 100 degrees and then sit there for about 45 minutes with some rev-ing now and again. Vid here

https://www.flickr.com/photos/58068042@N07/15383223135/

One of the nasty rattles I could hear that I thought was coming from the vanos turned out to be the water pump pulley screws working loose (about 1/2 a cm) which was slightly vexing. Once I'd identified that and tightened them up the rattles went but I was still left with the ticking and valve train noise which settled a bit over the hour.

I'm going to check the oil level again once cool and drained down and top up if necessary. I'll probably grab some of that Wynn's stuff Peter recommended tomorrow. I'm always a bit suspicious of these engine treatments but as the thing has done 150K it can't hurt to try.

I appear to have fitted the loudest rad fan in existence too. When that kicked in at ~95 degrees it drowned out all other noises which was a bit irritating. I struggled to get the oil over 80 degrees too, I believe it should be closer to 90-100.

One thing that was bothering me a bit was the oil pressure. I've never (unsurprisingly) owned a car with an oil pressure gauge so not sure what I should see. It sits at 1/2 a bar on tick over and then raises to about 2 bar when you rev to 3000 rpm but I never see it go higher. Is this correct behavior?
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Old 28th September 2014, 21:25
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One thing that was bothering me a bit was the oil pressure. I've never (unsurprisingly) owned a car with an oil pressure gauge so not sure what I should see. It sits at 1/2 a bar on tick over and then raises to about 2 bar when you rev to 3000 rpm but I never see it go higher. Is this correct behaviour?
Without checking my books,and based on my M20B28, I would expect about 1.3 bar (20psi) at idle rising to about 5 bar (75psi) at 2000rpm. So it does seem a bit low?
But before you panic about your engine, you may have a gauge/sender calibration issue.
Try some Wynns cam lifter stuff which can't do any harm and may free up any other gummed up oil ways. Worth a try?

Good tip about threadlocking the water pump pulley bolts.
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Old 28th September 2014, 22:38
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Hi Peter, just doing a quick bit of googling on the M50 oil pressure I saw a number of people say that 10-15psi at idle is normal i.e. 0.6 to 1 bar then you should see roughly 10 psi per 1000 rpm which would equate nicely to my 2 bar at 3000 rpm. I wonder if the M52 is different due to different pumps. I do have a Bentley manual a few inches above my head on a shelf which I suppose I could stretch up and open but I'd assumed as the e36 had no pressure gauge, it wouldn't tell me anything. I also read that oil temp would normally be around 150F idling going up to 190 cruising so my 80 degrees seems ok after all.

I normally do the complete opposite and go for copper grease everywhere rather than loctite as I'm sick of wrestling with seized and rusty bolts. In this case I probably had the pulley off some time ago and just forgot to tighten them up properly. I'll probably just use some spring or star washers on instead. It does make me want to go outside and check the water pump on my daily driver though
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Old 29th September 2014, 09:43
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Originally Posted by morris View Post
Hi Peter, just doing a quick bit of googling on the M50 oil pressure I saw a number of people say that 10-15psi at idle is normal i.e. 0.6 to 1 bar then you should see roughly 10 psi per 1000 rpm which would equate nicely to my 2 bar at 3000 rpm. I wonder if the M52 is different due to different pumps. I do have a Bentley manual a few inches above my head on a shelf which I suppose I could stretch up and open but I'd assumed as the e36 had no pressure gauge, it wouldn't tell me anything. I also read that oil temp would normally be around 150F idling going up to 190 cruising so my 80 degrees seems ok after all.

I normally do the complete opposite and go for copper grease everywhere rather than loctite as I'm sick of wrestling with seized and rusty bolts. In this case I probably had the pulley off some time ago and just forgot to tighten them up properly. I'll probably just use some spring or star washers on instead. It does make me want to go outside and check the water pump on my daily driver though
My guesstimates were a bit high...
my Bentley manual says 0.5 Bar minimum at idle and the pressure relief valve should open at 4 Bar 'at elevated rpm' whatever that means.
I think your 2 Bar at 3000 rpm does seem a bit low?
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Old 29th September 2014, 11:31
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Short runs on an m50/m52 causes the tractor level of noise which can be cleared with a good run in my experience.

Oil pressure on m20b28 starts high when cold the drops down. Goes up a bit under load when hot / higher rpm.
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Old 29th September 2014, 18:35
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Just took it back out on the drive and instantly the difference was obvious, so much quieter but still not quite right. I've dropped a bottle of that wynns stuff in to see if that helps but only had time to run it for about 10 minutes afterwards. I suspect it will take a lot more running to get that all through the system.

There's still too much vibration for my liking leading me to believe I may have a slight misfire. You can feel it though the seat when reving up past 1000-2000rpm and the rear view mirror shakes noticeably. At idle the front wings are vibrating as is anything resting on the chassis. I can hear a few small exhaust leaks too where I've not yet pasted the joints or probably tightened them up quite enough which won't help but shouldn't be enough to cause a vibration.

I checked the oil pressure immediately after starting cold and it was up at about 4 bar and then settles down to 1/2 once the coolant is heading towards 70-80.

I'm going to check the plugs next to see if there's any evidence of one of the cylinders not running cleanly
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Old 29th September 2014, 21:22
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Just took it back out on the drive and instantly the difference was obvious, so much quieter but still not quite right. I've dropped a bottle of that wynns stuff in to see if that helps but only had time to run it for about 10 minutes afterwards. I suspect it will take a lot more running to get that all through the system.

There's still too much vibration for my liking leading me to believe I may have a slight misfire. You can feel it though the seat when reving up past 1000-2000rpm and the rear view mirror shakes noticeably. At idle the front wings are vibrating as is anything resting on the chassis. I can hear a few small exhaust leaks too where I've not yet pasted the joints or probably tightened them up quite enough which won't help but shouldn't be enough to cause a vibration.

I checked the oil pressure immediately after starting cold and it was up at about 4 bar and then settles down to 1/2 once the coolant is heading towards 70-80.

I'm going to check the plugs next to see if there's any evidence of one of the cylinders not running cleanly
Good news on the oil pressure!

Have you listened to each injector to check they are all firing? If you hold a large screwdriver handle to your ear and then touch the blade end in turn on the top of each injector you can hear them clicking. (You have to take the plastic head cover off )
Even though I had my injectors professionally cleaned and flow tested I had one that was a bit reluctant to go at first. A little tap with the screwdriver got it going and it never caused any problem after that.

...peter
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Old 29th September 2014, 21:43
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my attempts at the old screw driver trick usually end up with me spiking myself in the head. I did give that a go initially but couldn't pick up on anything specific. I'm going to do the pull each coil off one at a time trick first to see if I can isolate the misfire, swap them round etc. While I've got the covers off I'll see if the injectors are ok at the same time.

I've been looking at some vids online and 2 missing cylinders on the straight 6 still doesn't produce that bad a vibration. my old v6 would feel like the car was shaking itself apart if even one coil had died. If I do find a dodgy coil I'll order a set of new plugs at the same time as I've no idea how old the current ones are.
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Old 29th September 2014, 22:55
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well, pulled all the plugs out to take a look and it's not good. All are equally sooty so the engine has obviously been running rich and without a good blast that problem isn't going to sort itself out. Al that muck isn't going to help with getting a good spark.



I'll try cleaning them up tomorrow night and give it another run as the various short runs over the last year or so may have been enough to clog them up. Now that the O2 sensor isn't exposed to atmosphere, that should help too.
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Old 30th September 2014, 18:35
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I've just been out for another test with cleaned up plugs and the good news is that none of the cylinders are misfiring, at least not constantly so the plugs and coils are serviceable. Pulling each coil in turn resulted in a misfire which cleared immediately it was replaced although number 5 did hesitate a second or so coming back in.

I also did the screw driver against the head trick on all the injectors which were all ticking away nicely. The same trick on the chain tensioner also showed no nasty noises as I'd come to the conclusion that it could be a highly probably source of the rattling. Using the same trick I've narrowed to the source of the rattling sounds to the front of the head on the VANOS housing only including the solenoid. If you move to the block, the water pump housing or even the head directly behind the VANOS you just get a nice swirly noise of things rotating smoothly so it looks like I've found the culprit.

It may still just be a case of the car needing an Italian tune up down the dual carriageway but that's not going to happen until the spring post IVA so I'll pop the rocker cover and VANOS off over the winter and investigate further with a view to replacing the offending seals etc. There is always a chance that it's the top chain tensioner that is kaput but that is impossible to replace as far as I can tell without locking the cams (the tool for which I don't have).

As always, thanks for all the pointers.
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