bent pusrods

[chris52]

Still on the search for the tapping noise and after yet another strip down I straight edged all the pushrods. I found 2 were slightly bent by about 1mm also saw possible signs of contact with the guide holes but as the pushrods are only a couple of hundred miles old the marks were not very definate.
So the tapping could be the pushrods? why would they bend in such a short space of time or is it possible they were manufactured like this?
Also noticed that the the rods didn't seem to seat in the center of the guide holes in fact some were less than 1mm clear and sat quite a way to the right. Surely they should sit central with movement only up and down with the movement of the rocker?

Your thoughts on this would be appreciated
Chris

[Boosted LS1]

If they're bent you will have excess clearance in the valvetrain so yes, they could be the cause of your tapping noises.

[chris52]

well its not the pushrods as I replced the two bent ones and still tthe tapping persists, I am running the car now with the rocker covers off but still can't locate where the tapping is coming from as it seems to be all over even with the mechanics stethascope I cant say which ones are noisey.
So the search keeps on going
Chris

[spend]

How can you be so sure that replacing bent / scored pushrods with new ones has stopped the pushrods catching??? Its just about impossible to see where the pushrod is at full lift when using fluid followers IMHO, about all you can do is rag it and then strip/inspect them again..

[chris52]

spend said:

How can you be so sure that replacing bent / scored pushrods with new ones has stopped the pushrods catching??? Its just about impossible to see where the pushrod is at full lift when using fluid followers IMHO, about all you can do is rag it and then strip/inspect them again..

I coloured all the pushrods with a thin coat of ink ran the car with it tapping then removed all the pushrods inpected them and the ink was still intact no scoring whatsoever or rubbing of the ink. So I am pretty sure that the pushrods are not catching.


Chris

[GreenV8S]

spend said:

Its just about impossible to see where the pushrod is at full lift when using fluid followers IMHO, about all you can do is rag it and then strip/inspect them again..

Outside the engine I'd put some tape on the stationary part, or paint the pushrod and see whether anything got scraped off. I'm wary of doing that inside the engine because you don't want stuff falling off inside, but perhaps you could find a safe way to do it.

By the way, after replacing the pushrods were all the preloads checked and reset?

[chris52]

Ok seems like I have finally got to the bottom of it and I now have no more tapping

The Cure was as simple as this, there wer 7 rockers that were dated 94 part no HRC 1050 1 and 2, they looked identical to the other folowers dated 96 part no HRC 1050 14 and 15 but on close inspection there were slight differences mainly where the pushrod sits in they for some reason sit in a lot deeper than the others which obviosley knocked the preload out by quite a way on those cylinders. Now I havn't road tested the car yet as I need to get the rocker covers back on but I did let it run up to full temp and not a tap was to be heard so fingers crossed its cured.

Will report back later after a good road test but it may be quite a while before I get back

Chris

[GreenV8S]

chris52 said:

obviosley knocked the preload out by quite a way on those cylinders.

Sounds as if the person who checked the preload all those times while you were chasing this noise needs a slap.

[chris52]

GreenV8S said:

chris52 said:

obviosley knocked the preload out by quite a way on those cylinders.

Sounds as if the person who checked the preload all those times while you were chasing this noise needs a slap.

Yep I think your right' when I first rebuilt it after the cam change I set the pre-loads myself and to be fair there was no tapping but I had low oil pressure due to the new rockers I was supplied,I then used the origional rocker just replacing the ones that had lost there tips,the oil pressure came back but the tapping also came back, At this point I sent it to a local garage that came recomended by someone from the TVR club, he checked the pre-loads and found them to be too low, he then had the pedestals skimmed and told me that all the pre-loads were spot on, but the tapping was still there and he didn't have a clue why. Now I am only guessing that these rockers were knocking the pre-load out, maybe it was something else but to be honest I don't care I am just glad to get it running well FINALLY, just got back from a nice run out in the yorkshire dales and boy its running well no tapping whatsoever, a massive increase in performance, much smoother, engine temps running a little cooler, the idle is a lot steadier altogether its just running great

BRING ON THE GROWL

One big bonus to all this messing about is how much I have learnt, and also, how so many people are ready to give help and advise, So a big thanks to everyone.

Chris

[LordGrover]

Nice one. Pleased you got it sorted.

[crackedfinger]

(this may be a daft question, please bear with me!) Interesting read as I've a tap to chase too, I'm a little lost on how the rockers affect the oil pressure?

[chris52]

The rockers I was supplied with were not a TVR origional part they had a part no stamped on the side 602513 which is a part no for the rover rv8 engine, these rockers had a large oil gully at the top of the rocker and basically just spewed oil out which dropped the oil pressure. I ran these with the rocker covers off and you could just see the oil pumping out. I contacted the supplier and was told these rockers were the origional equiptment rangerover rockers and he fit them into all his race engines that he built and never had a problem. there is a thread on the chimp forum about these rockers under the title "The Dreaded Tick" worth having a good read of it to avoid going down the same path we did.

Chris