Lude Generation

Just bought a 55k mile, full Honda service history 2.3 Prelude (4G, H23), and it was a bit rattly so I got the local garage to check the valve clearances before I drove it all the way up to my folks' house 300 miles away. The car is now a little quieter, but still quite rattly; the mechanic said the tappets were a 'little bit out', but not much.

Just changed the oil to 5W40 full syn and got it flushed beforehand too; again the engine is slightly quieter but there's still a definite rattle that sounds a bit like a loose camchain tensioner (but there isn't one, obviously). It doesn't sound like the engine is about to blow, but there's definitely more 'clack clack' than I'd expect from a low mileage, FSH Honda engine...

Any thoughts? Should I go for another engine flush and oil change soon? Is there anything else that could be the cause of a slightly dieselly sounding H23? Something obvious that I haven't thought of?

get the clearances done by someone who knows what they are doing

I'll get it over to Rich at Performance Autoworks when I have the time, but in the meantime any other possibilities? Anyone else have 'clackety' 2.3 Ludes?

is this a auto or manuel
either way it wont thank you running 5w/40 that is a thin oil to be running 10/40 semi syn

my 2.3 auto did get a little noisy but doing tappits and new plugs and 8mm upgraded leads seemed to sort her out

The manual says it's okay to run 5W30 from between -20 to 35 degrees C, and similar for 10W40 so I'd have thought 5W40 would be fine? Semi syn is a waste of time in my view because oil is only as good as its weakest link, which is the mineral oil part of it! So best to use full syn...

5w/40 is fine. Its what nearly all fully synth comes in... I have run it for 10 or more years

5w40 is indeed fine, I wouldn't think it'd be that. The H23 uses a manual timing belt tensioner, where is the rattle coming from ?

get a long handled screwdriver and put it against different parts of the engine and the handle to your ear - you should be able to narrow it down - start the engine and get a mate to rev it slowly etc check the alternator, power steering pump, manifold, block at the top and so on
you might also need to get under the car and check the exhaust at the front underside

Seems to be coming from top end of the engine, don't think it's ancillaries.

Sorry if this is a stupid question, but can non-hydraulic tappets rattle, even if the clearances are set right? Could I have a sticky tappet?

The reason I'm wondering this is after a long run the engine seems to quieten down a bit, then start clattering more on idle after a short while. Could it be gunge inside that's sticking the tappet slightly when the oil pressure is lower, on idle?

It could have sticky lost motion assembly's.