Race Engine Forum UK

Frequency - I think - may be may be too high for a rod bearing and it is quieter when you rev up.

Check the water pump, alternator bearings and cambelt tensioner pulley.


G

Thanks Guy, I did suspect the water pump as that is around the area the noise is coming from, but it spins nice and smoothly by hand with no play - although that may be different when warm and under the load of the belt. Likewise the alternator, although that is on the other side of the block anyway. I suppose I should have ran it without the drive belt before I started pulling it apart! I've not checked the tensioner yet, so that is still a possibility. Either way I've committed to pull it out and rebuild it now, its long over due. Hopefully I'll get a few hours on it this evening.

I got back from work at a reasonable time this evening so had time to get start the engine removal. I decided to first pull the head and manifolds off in one lump to keep things manageable. After that I pulled the water pump and then the bottom pulley and cam drive, and I think I have found the source of the knock/tapping. The keyway in cam belt drive looks to be damaged allowing it to move on the crank a few degrees. I had some issues in this area before, having to replace a damaged woodruff key, so must have missed the real cause. I'm not sure that the crank pulley fit is entirely correct either as it has an extra groove for driving an aftermarket AC compressor that was part of the Anniversary package. I assume that the knocking at idle was the drive hitting each side of woodruff, and the fluffiness was the resulting timing shift (potentially misfiring the injectors too which are driven from the LT side of the ignition). It may also explain why the noise disappears when being revved as the cam drive would tend to be forced to one extremity of the play.

nice post but I think your conclusions will prove to be wrong...

G

Quite possibly Guy, do you think the real answer may still be in the bottom end? Hopefully, I will get that apart at the weekend.

I'm afraid that only a thoroughgoing inspection will now tell..

the only possible cause of a knocking noise from the crank front end would be the front pulley but was visibly loose. And when that is the case usually the whole assembly comes apart and the parts 'brain' somebody in a following car on the M25 motorway, or similar...

(so to say....)

I guess we will see...

G

Simon,

I just wanted to say I'm very impressed by the quality of your work, great stuff and great posts!

thank you, Phil G.

That's very kind of you Phil, especially given the meticulous standards you have applied to your Spider - it's superb!

I managed to get the engine out over the weekend, and strip, inspect and start some fettling on the crank and block over the last couple of evenings.
In terms of any evidence of the cause of the knocking, I couldn't find anything in the bottom end. All caps were still torqued and the crank measures out just above lower limit (one journal was .1 thou below). I'm sure the problem was the woodruff, pulley and cam drive - it was a mess and as far as I can tell the only thing preventing the drive moving on the crank was the friction between the pulley. This was not loose but the bore was gouged.

See the movement here:
https://vimeo.com/161391035

Some more pics coming up...

Shots of the 'cheesey' words and damaged slot in the cam drive.


Having decided the crank is serviceable after a clean up I spent the last couple of evenings performing Guy's published unplugging operation.
Attention turning to the block: That's about it for now, looks like I will need to be contacting Guy for some shiny new bits and pieces fairly soon!

have you modified the aux driveshaft?

The fuel lobe can hit no2 rod..

G

Hi Guy,

No, I've not modded the aux driveshaft (I will be on this rebuild though), the engine has never been apart, other than the head being off a couple of times and I always refer to the diagram in the Haynes manual for the positioning of the aux drive and cam wheels when disturbing the belt, but I could have screwed this up! There was no evidence on the rod or driveshaft cam of interference, although this may have been obscured by oil etc. I'll take another look though. Also, the noise only started occurring when I started it up a month or so ago to dry it out after sitting out on the drive, prior to that the cam belt and wheels haven't been disturbed since March 2013. Is it really possible that the cam lobe/rod could have been close enough to interfering throughout the three years and wear and tear has as now brought them closer together?

I'll contact you in the next few days about arranging the re-bore/pistons/rings, and ordering up bearing, gaskets etc.

Really nice car and fantastic photostory, I am a big fan of your job.

It's possible Simon, assuming that the shaft -rod clearance was a bit 'borderline' in the first place..

Have a look on no 2 rod - near the bolt head - for a 'strike mark'...

G

Sorry for the very belated update. Work on the Spider has been on the 'back burner' for a while whilst working on the VW (engine build and bodywork), much prepping of my Jeep for a Pyrenees trip last August, and various other activities. I've now turned my attention back to the Spider's engine with the intention of having it ready for some summer club events.

I revisited to the potential aux shaft/ No 2 rod interference problem but couldn't see any evidence of contact. But I've now modded the shaft and as per GC's recommendation to eliminate the possibility of problems in the future. For the last couple of weekends I've been finishing off the prep of a spare head ready to fit the GC race guides I've had for ages, and prepped the FI inlet plenum and manifold which I'll be retaining for this build. I've not really got time for a detailed run down of everything I've done, but here are some pictures of progress.
Over the winter months I discovered a lucrative sideline in repairing vintage hifi, which has funded a small 7x14 lathe and a press. So last week I played around with turning down the crank pulley to fit a trigger wheel for the Megavolt ignition and/or Megasquirt FI to replace the LE Jetronic. I also made up a valve guide insertion tool, and a jig for the press.
Hopefully I'll get the guides fitted this weekend and move on to prepping the valve seats.

Impressive Simon! Keep it up.

Regards,
Charles