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Cambelt, to change or not?

Posted by Flyboy 
January 03, 2011 08:07AM
Hi All, I trust everyone had a peaceful and blessed Christmas, and all my best wishes to everyone for the new year, may it be filled with joy and prosperity.

Ok, so this year Santa came bearing BMW gifts, in the form of a new camshaft, rockers and lifters for the little 318i, so hopefully I will get rid of the valvetrain noise that has been driving me scatty.
So this weekend or next I will be fitting said parts, I replaced the cambelt with all idlers and tensioner about six months ago, and I figure the belt has done no more than 10 000km since it was put in.
Now one school of thought, says, no matter what the milage, if you take a belt off, you must replace it with a new one, and never use the old one again, but then again if it is only 10 000km old and has not been pinched or damaged on removal, what is the point.
What do ye say, and why?
Do I put new or not?

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
January 03, 2011 10:49AM
The expense of replacing a near new belt would work on my penny pinching heart too. But think ahead and think how much it will postpone the next change that comes along sooner than you expect. The delay of that change for the year or so that it brings may be worth it. I like things to stay fixed as long as possible.

Bob in Everett
January 03, 2011 01:40PM
And how would you feel if the belt snaps in a couple of months?

I'm not a fan of spending to much money, but I wouldn't save on a timing belt.
January 03, 2011 02:34PM
Quote
Michiel 318iS
And how would you feel if the belt snaps in a couple of months?

I'm not a fan of spending to much money, but I wouldn't save on a timing belt.

Well, he does state he replaced the cam drive componentry 6 months ago. If I was working on a car that had a 6 month old fan belt or cogged drive belt, I can't necessarily say I would replace the belt as part of the repair. Obviously, the issue here is that the belt is buried inside the front of the engine, but it does raise an interesting dilemma none the less.

alan
January 03, 2011 03:06PM
If, in the course of doing all the other stuff, the belt is exposed or removed, I would simply replace it...if I remember, it's only $40 or so.
However, if the belt doesn't get exposed; then I would leave it alone.
January 03, 2011 10:21PM
Thanks guys, I will replace the belt, to be on the safe side, although I know that when I take it off, it will be like brand new, I was always taught that if you remove a cambelt, it should be replaced, regardless of milage done or age, I just wanted to try and see if someone could explain the logic to me, as I said, it has done about 10 000Km, if that, and what is the recommended interval for changing them, 70 000Km, or something to that effect? Just seems such a waste, especially now at this time of year when cash is tight after the Christmas season, but I suppose it is a bit stupid having spent $230 on camshaft, rockers and lifters, then skimp on a $20 belt, I guess if nothing else, it buys peace of mind.

Can't wait to get my new cam in and see if there is any noticable diffirence in power and fuel consumption, If there is any interest, I will put together a photo article, step by step log of the job, for endless collection of good info already on this site.

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
January 04, 2011 12:35PM
Always nice to read!
January 08, 2011 06:43AM
Ok, so today the new cam, rockers and lifters went in, no stress, no fuss, was done by lunch time.
When I tried to start it, it sort of fired once or twice, then nothing, just cranks over and does not even attempt to fire. :furious:
Check everything over, pull a plug lead and check for spark, checks out fine, not strong but it has spark, pull the distributor cap again, check that all that is inside is good, it is.

So my spark is there, my compression is there, no, my cam timing is not 180 degrees out, so that checks, so I start looking at the fuel side of things, I pull the pipe off that feeds the rail, after the fuel filter, where it clamps onto the rail.
Now like all BM's mine has a pump in the tank, and I would assume that as soon as the ignition is switched on, the pump would run and pressurise the fuel system, so I but a rag under the pipe and an ice cream container to check for fuel.
When I turn the key all the way to "Run", nothing, as soon as I start cranking the engine fuel gets pumped out of that pipe, and as soon as I release the key back to "run", the flow stops, is this normal??????
Or by some freak coincedence I now have a bud fuel pump in the tank that is gong to cost me another three grand???????
I chucked some fuel into the intake boot and it wanted to.:furious:
Any help or suggestions?

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
January 08, 2011 07:25AM
If I throw fuel into the intake pipe, between the manifold and the air flow meter, it fires right up, and then dies, as the fuel is all used up.
Maybe the in tank pump, or the pump relay? Where is the fuel pump relay situated, I may swop it out with one of the other relays to check it before throwing three grand I don't have at a pump.:cry:

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
January 08, 2011 08:06AM
Quote
Flyboy
When I turn the key all the way to "Run", nothing, as soon as I start cranking the engine fuel gets pumped out of that pipe, and as soon as I release the key back to "run", the flow stops, is this normal??????
I'm pretty sure this is normal. IIRC the fuel pump does not get power until the engine is cranking. The Bentley manual has procedures for testing the fuel pump, and it's a bit more complicated than turning the key. That's about all I can remember about it at the moment, though.
Quote

Or by some freak coincedence I now have a bud fuel pump in the tank that is gong to cost me another three grand???????
Three grand for a fuel pump?? A new pump should be around US$250, and it's about a 10-minute job to replace.

Sorry I don't have any better ideas about your non-starting problem, but I would bet that it's not the fuel pump.

__________
Dave
'91 325iX
January 08, 2011 10:44AM
Quote
Flyboy
If I throw fuel into the intake pipe, between the manifold and the air flow meter, it fires right up, and then dies, as the fuel is all used up.
Maybe the in tank pump, or the pump relay? Where is the fuel pump relay situated, I may swop it out with one of the other relays to check it before throwing three grand I don't have at a pump.:cry:

Is the fuel pressure regulator hooked back up...the little vacuum hose?
January 08, 2011 10:52AM
It is Pete, never touched it at all, but did check to see that the little vacum hose was still on, all is good there.

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
January 08, 2011 10:58AM
OK, the car starts for a few seconds in the key start position. What causes the fuel pump to shut down in a non-start condition. That's where I would look. Crank position sensor?

alan
January 08, 2011 11:34AM
Hi Al, maybe, but I never removed or even unplugged it, in fact all I did was clean off the sensor with a cloth while the pulleys were off and it was easy to get to.
I does run in the run position after you release the key from start, but ony for a few seconds then it is as if it is starved of fuel, and dies.

----------------------------------------------------------------------------------------------------------------------------------
E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
January 08, 2011 01:14PM
Quote
Flyboy
Hi Al, maybe, but I never removed or even unplugged it, in fact all I did was clean off the sensor with a cloth while the pulleys were off and it was easy to get to.
I does run in the run position after you release the key from start, but ony for a few seconds then it is as if it is starved of fuel, and dies.

Check out the main relay. I'm not sure about your model but on some, the fuel pump relay only picks up if the main relay is activated...
January 08, 2011 01:54PM
Peter, I checked, seems there is no power to the pump, even with the relay bridged (in effect, putting the pump hot onto the battery).
Looking at the diagram, it seems simple enough, battery -> relay -> fuse 11 -> pump.
So I will take the multi meter to it and start stabbing wires from the battery down stream until I get to the pump and try and find the break.
Yes the fuel pump relay is connected to the main relay via pin 86, but bridging the relay bypasses that and puts the battery straight onto the pump wire.

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E30'S AREN'T BUILT, THEY'RE CAUGHT IN THE WILD!!!



When in doubt, use full throttle,
it may not improve the situation, but it will end the suspence.
January 08, 2011 03:39PM
Well, good luck on the troubleshooting. Once you have the meter working for you, I'm certain it will only be minutes before you find the 'break'; just :stickpoke: until you find it smileys with beer
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