Tap tap tap

[ianf]

It could also be a loose carb' I had this problem & finally realised what the problem was talking it through with a friend. "I have a top end tapping noise on the inlet side, sounds like a valve clearance - it's just like the loose exhaust manifold tap on my old Midget..........ah". My noise did come go with engine temp' I think it was worse hot.

Good luck.

Ian

[DrEntropy]

Check clearances first, as that is the most likely cause. The bucket sleeves can be suspect if the engine has had abuse in the form of overheat. They can rotate in the alloy head and the cut-outs become misaligned. I've an old Stromberg head here with the sleeves well and truely knacker'd from cam lobe interference. Literal CHUNKS taken out of 'em. Never saw how badly the cams fared from this. Another overheat related "half-failure" is: guides can change position and interfere with valve operation.

BTW: Not from any of MY cars, it came with a pile of used spares I once purchased.

[Robbie693]

Thanks Doc,

The car has been running hot since I bought it, sometimes gets up to 100deg, never gone into the red though. What kind of temperatures would lead to these kind of problems?

The head gasket has gone so I need to get the head off anyway and check for warpage. I'll check eveything else at the same time. I also need to find out the cause of the hot running

[jeff jackson]

My 72 big valve taps as well. Be interested to see your findings.
I rebuilt my engine 2K miles back. The head was rebuilt QED, but on re-assembly to the block by me, two valve clearances were waaaay out.
I set these two mid range, and I still get the tapping, so I am not convinced I did the right thing by changing them, ( after the amount of money QED charged me) or I got the clearances wrong again.
Need to check the clearances again during the winter layup.
Should keep me occupied fro a while!!

Jeff 72+2

[Pastapesto]

Hello Robbie
I used to have a really nice +2s 130 "DRX 831K" in (Porsche) Royal Blue (anyone know anything about it these days, I sold it in about 1996) anyway I seem to remember that I had a tapping noise that seemed to come from the metal servo pipe that runs from the intake manifold around the back of the engine on the bulkhead to the servo via a rubber connecting hose. I think from memory that it was attached to the bulkhead by one or two "P" clips and for some reason (probably as you said from the non-return valve chattering) it made a ticking sound and was amplified by the natural sound box design of the bulkhead/dash assembly. Try removing the "P" clips and see if it makes any difference. If it does then try some rubber/foam to insulate sound & if not, then it was worth a try and only simple to check. Sometimes these annoying problems wind you up so much that you cannot see the forest from the trees and many times to my cost have overlooked the simple items.
These days I am driving a Sprint & loving every minute, problem is though I have two young children & so there are very few minutes to enjoy. I should not have sold the +2 (dohh!..) but my wife wanted a nice new kitchen & I was having trouble garaging it at the time ....ho hum.

Anyway I do hope that you fix it. Let us know if you do.

Regards

Adam

[DrEntropy]

[quote=Robbie693] The car has been running hot since I bought it, sometimes gets up to 100deg, never gone into the red though. What kind of temperatures would lead to these kind of problems? [/quote]

100* C?!? Sustained running at that temp would be enough to have concerns about the bucket liners and guides, methinks. A good thorough inspection of both is in order.

As for the cause(es) of hot running, first prudent step would be to have the radiator gone thru by a good shop. Whilst the head's off have a reckkie down in the water jacket. Probe the thing with a wire coat-hanger or suchlike to see if/how much rusty sludge may be in there. Aught you could do short of full disassembly and a "boiling" if there's a real build-up, tho. After the head is back in situ you could "flush" the block/head with a hose-pipe and a good pressure by stuffing the hose into the lower outlet and letting water run until it appears clear. Thermostat out, housing in place. Messy and "stop-gap" but better than NOT doing it.

[Robbie693]

Thanks Adam, I'll have a look at that.

Doc,

I have back-flushed the engine twice before and used a flushing agent. The water always ran clear from the block, although the radiator was a bit bunged up. I am going to get it looked at but do rad shops test for blockages or is it a case of recore it just in case?

I think the head gasket may have been leaking since I got the car some 18 months ago - there was oil leaking from the front near the timing case on both sides when I bought it, but I assumed it was the head to timing case gasket. Now it is leaking from further along and I have a bit of water at the back of the head so if it hadn't gone before it certainly appears to have gone now.

Would a blown head gasket cause hot running?

[DrEntropy]

Yup. And some other nasty side effects. Time to yank the head.

A competent rad shop ~should~ do what's called "rodding" the rad: run a rod thru all the capillary passages. Keep in mind: a 30% reduction in rad flow will result in an 80% loss of efficiency. Recore it if it's bunged up. Better SURE than have a regret later. If the block runs clear on a backflush you may be good to go after the recore and head R&R.

[Robbie693]

Thanks Doc, here's hoping the head isn't warped

[DrEntropy]

Highly unlikely! Alloy heads can take some serious abuse before they twist!

[twincamman]

I think the buckets have been mixed up during the rebuild ---they should always be assembled in the same sleeve from which they were removed ---------ed

[DrEntropy]

Yup. Like pushrods, they "bed" to their partners... each one should be put back into their respective bore.

[Robbie693]

Highly unlikely! Alloy heads can take some serious abuse before they twist!

Thats encouraging - thanks again Doc

So how do I find out which bucket goes in which bore?

[twincamman]

LIVE WITH IT -----There is little you can do except disassemble everything mic it up reassemble --listen for the tic and if its there repeat as needed -- -ed