My Alfa Romeo 33 rebuild - FIRST TIMER

[Guy Croft]

Cam housing wear would not make the noise you are hearing. It is something in synch with valve operation or rod motion.

G

[Brit01]

Cam housing wear would not make the noise you are hearing.

Yes very true but the tappet housing wear would have an effect as previously mentioned.
Too much clearance in the bucket when hot and then loss of oil pressure(bleeding out) in the tappet causing the ticking.

The NOS cam boxes are very tempting indeed. Eliminates any possibility of bucket wear.

[Brit01]

Pictures of lobes and tappets after 100 kms break in.

[Guy Croft]

MODEL POST!

Excellent follow up, you might be a 'first-timer' but you learn real quick! I could not ask for better. I would be for shoving the tappets into their respective bores rightaway and seeing how much 'rock' they have dry - and then oiled-up. To make the rather obvious noise we are hearing they (or at least one of them) would have to have a lot of unwanted side-clearance..

G

[Brit01]

Thank you Guy.

This was done one handed while trying to feed a very hungry grumpy 17 month old baby at 9.30 pm after a hard days work!! Lol

I think I will bite the bullet and go for a pair of NOS cam supports from Argentina. I placed a tappet in each bucket, they rocked slightly in the current buckets and also more in the spare I got.

I don't want any more issues with worn out buckets (considering these are from 1988).
I can get the NOS supports pretty quickly due to a contact.
I will assemble one when it arrives and in Dec when I have 2 weeks holiday in our beach house (private driveway and lots of space and light - mechanics heaven), take off the left head and replace the old cam support with the second NOS.

Then I will have piece of mind. News cams, tappets and new cam supports.

I found a supplier who has 100 original 0km boxer engines in Argentina who sells for parts or whatever you want. What a treasure.


I'll keep you updated.

Many thanks as always.

Chris

[Guy Croft]

I'm not sure you are right to pursue new supports quite yet. You might be right but you may not be and it's a heck of a lot of time and money wasted if you're wrong.

All bucket type tappets rock a bit though less so when oiled up. However given that they are energised by oil pressure holding them against the cam one end and sit on top of a valve spring the other the chances of them rocking to such an extent that they are generating that awful noise from excessive clearance is not great per_se.

I spoke to my long-time garage owner friend in Welllingore Lincs and he has encountered defective new tappets. But other than referrng to low oil pressure or worn housing or that cause (unlikely twice, in all conscience) he has no new suggestions.

But he did tell me that before re-installing your new ones you need to squeeze the oil out progressively from each one in a vice. You have to be patient - don't lean on them too hard - give them a chance to evacuate slowly. You should feel strong resistance and if you don't and the oil just shoots out the tappet is u/s. You should do this to your tappets and report.

Is it just possible that an oil feed to one tappet is restricted in some way? Check that out would you?

Sorry - but I wish I knew this engine better.

G

[Brit01]

However given that they are energised by oil pressure holding them against the cam one end and sit on top of a valve spring the other the chances of them rocking to such an extent that they are generating that awful noise from excessive clearance is not great per_se.

I agree with you here. I would think that if the clearance has exceeded the fact spec of 35.025mm then as it losses pressure around the tappet the valve inside itself bleeds out and does not hold it's oil pressure inside hence the ticking.
It is dead quiet when cold and with high oil pressure due to the cold thick oil.

I spoke to my long-time garage owner friend in Welllingore Lincs and he has encountered defective new tappets. But other than referrng to low oil pressure or worn housing or that cause (unlikely twice, in all conscience) he has no new suggestions.

Thanks for this. Yes too much of a coincidence, same tappet in same bucket failing. And if it had failed then it would make a noise on the cold start up also.

But he did tell me that before re-installing your new ones you need to squeeze the oil out progressively from each one in a vice. You have to be patient - don't lean on them too hard - give them a chance to evacuate slowly. You should feel strong resistance and if you don't and the oil just shoots out the tappet is u/s. You should do this to your tappets and report.

Is it just possible that an oil feed to one tappet is restricted in some way? Check that out would you?

I will do that. I did do a quick squeeze of each one briefly and a tiny amount of oil came out and you could see the tappet rise again due to the spring inside I assume.
I will squeeze each one tonight to investigate further.

Thanks very much.

I can foresee myself ordering these new cam supports in the end and pretty soon.

Something to note also.

The middle bearing of the camshaft is part of the pressurized oil channel that leads to the tappet oil feed holes.

If this bearing is also worn the oil will bleed out into the cam box and also reduce the oil pressure feed to the tappets.

[Guy Croft]

mmm - losing pressure there...

Chris, I would not expect a worn cam housing to be contributory cause in itself though if the oil pressure is low it would not help.

You need a minimum of 50psi hot (the pressure goes up and down with rpm) and preferably 55psi. More is better but if you want a max - your unit certainly doesn't (in any event) need over 70 hot. That is not a general rule for all engine types BTW. Cold measurements mean nothing. The more things in the pressure line (like 8 hyd tappets) the more you need. Under-pressurised lifters will rattle because they can't maintain contact with the cam base circle and it would be a potential cause of the wear failure in the 1st instance.

What exactly is yours developing hot? If you don't have a reliable capillary gauge to check it you need one..

Did you measure the pump clearances and check the relief valve? Refer me to the page here if that's been posted already. You haven't inadvertently left an O ring or gasket off the oil pump/system somewhere have you?

G

[Brit01]

What exactly is yours developing hot? If you don't have a reliable capillary gauge to check it you need one..

I have recently bought an electric gauge (just for safety reasons really with my wife and kid using the car). They would never know if the line started leaking.

Gives me a rough idea but yes not so accurate especially at lower levels I know.
But have been thinking of getting a mechanical gauge recently to compare.

The oil pump was reconditioned with brand new helical gears made of the smallest clearance possible. The valve also also works very well. It opens at 87 psi. When cold the gauge shows 87 psi at idle (and when revved) so I assume this valve is opening correctly. It was checked.

Then once warms up it can keep a steady 50-55 psi above 2500 rpm.
When the ticking appears after the fan kicks in (engine at it's hottest), the pressure gets a little low down to 15 psi at idle but does jump up quickly when revved.

The pump itself does not have any o-rings or gaskets luckily.

[Guy Croft]

Sounds OK to me!

G

[Brit01]

Good to know.

Thanks Guy.

It's a real shame Alfa didn't build the alloy cam supports with changeable bearing parts(shells) and bucket sleeves, NOT cast into the block.

Almost everything else on the boxer is re-buildable except these cam supports. That's why I'm pretty sure I'll snap up the NOS cam supports from BA while they are available.
Quite a find IMO.
Never seen them in Europe. They must have purchased the NOS stock from the Italian warehouse.
100 complete 0km boxer engines from the 80's!

[Brit01]

Just as a reminder this was the old lobe and tappet on the affected bucket. Took a real pounding especially in the last hot summer. I can imagine that pounding the tappet side to side in the bucket.

[Brit01]

you need to squeeze the oil out progressively from each one in a vice. You have to be patient - don't lean on them too hard - give them a chance to evacuate slowly. You should feel strong resistance and if you don't and the oil just shoots out the tappet is u/s. You should do this to your tappets and report.

Is it just possible that an oil feed to one tappet is restricted in some way? Check that out would you?

All tappets showed very strong resistance with only a small amount of oil evacuated slowly.

Squirted pressured penetrating oil from a can and nozzle down the passages and shot out all over my trousers!! No blockage there for sure.

[Guy Croft]

Not a defective tappet then, good.

G

[Brit01]

Nothing else left to change but the cam supports now I guess.

Trying to arrange the import of them from Argentina. Hopefully in a week or 2.

0.025mm allowance for wear on the buckets is so so small, after 24 years of use (21.5 years previous to my ownership totally unknown maintenance work) they are showing signs of wear.

If you can visually see wear then it is obviously more than the 0.025mm allowed wear on the alloy bucket/sleeve.

Keep you updated once I manage to get hold of a pair of the new cam supports.
With photos of course.

Thank you