Help needed - Oil Pressure & Pinking on new Cosworth engine

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Korres

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Hi forum,

Its my first post and i hope you will be able to help me.

I am the owner of a 1990 190E 2.5-16v. Very recently i had the complete engine rebuilt, so thats new valves, pistons, seals, chain etc, etc.

Since the rebuild i get pinking or pinging under acceleration. Its like a metallic rattling noise. I have checked to see wether there is anything loose and there is not. I have taken it to a bosch center and they cannot find any faults. But it only started after the rebuild.

Also when the engine was rebuilt its first fill of oil was 15w 40. Then i changed it at 500 miles with 10w 40 (semi synth) then a further three times up until 2000 miles with mobil 1 0w 40 fully synth.

A month or so after the rebuild the oil pressure began to drop just under 3 bars. Now several months later its just over 2 bars. But goes to 3 upon acceleration.

Can anybody shed any light on what is going on and how i can resolve these issues?

Thanks

Korres
 
There are many petrol stations selling poor quality fuel. Try optimax or a derivitive of.
 
Hi,

I have always used either shell v power or bp ultimate with no discernable difference?
 
Did your engine rebuilder skim the head or reface the block during the rebuild? This might lead to a slight increase in compression ratio. might be rectified with thicker head gasket or opening up the combustion chambers slightly. you could also try one of the "octane" enhancers to test whether it is pinking?
 
well the company in question is crewe engines. They said they refinish the head to the manufacturers specifications?
im thinking about the octane enhancer, but im using super unleaded as it is? :crazy:
 
I think Grober may have hit the nail on the head there.
 
also i have noticed that my poly v belt is worn and shiny...
could this be it?
this was removed during the build, maybe when it was put back on it became even more slack?
 
test purposes

also i have noticed that my poly v belt is worn and shiny...
could this be it?
this was removed during the build, maybe when it was put back on it became even more slack?
a loose poly V belt normally gives a screeching/squealing sound not like the sound you describe at all.dont think its that. I suggested using an octane enhancer to TEST for pinking. If adding the enhancer reduces or eliminates the sound then you have a good idea that is the cause of your noise and then decide on a solution. I wasnt suggesting you use it as a permanent solution.
 
so what may i ask is the solution?
also any thoughts as to the oil pressure?

much thanks
 
Is this zakh's car?
 
Oil pressure sounds fine. It will drop down form 3 when the oil get hot, they do this on a new engine so yours should be fine. It states in the MB manual that as long as the oil pressure remains above 0.5 on idle and increases to 3 when revving, its fine.

With regards to the pinking, these are highly tuned engines so i suggest having the ignition timing check and possibly retarded.
 
hi klp really appreciate the reply and reassurance.
on this car there is a ignition switch on the right wheel arch that has the settings S,N,2,3,5,7 i think...The bosch service center told me to switch to N, which i did and the pinking was almost all gone. But the downside was loss of power. Also i have read in the manual that its not a good idea to switch it to N?
 
hi klp really appreciate the reply and reassurance.
on this car there is a ignition switch on the right wheel arch that has the settings S,N,2,3,5,7 i think...The bosch service center told me to switch to N, which i did and the pinking was almost all gone. But the downside was loss of power. Also i have read in the manual that its not a good idea to switch it to N?

That switch alters the timing on the ignition. I would increase it from N to 2 first. If there is still no pinking, just keep increasing it. When it starts, just go back a notch.
 
What does Crewe have to say?

zakh was the owner of the most troublesome 2.5-16 in the UK, which he sold to some poor unfortunate. His engine was also rebuilt by Crewe.
 
thanks klp i shall give that a go...right now its in position s...shall i increase it to two?
 
thanks klp i shall give that a go...right now its in position s...shall i increase it to two?

Yep, just go up one notch at a time. If its ok go up another one, but when it starts to pink just turn it down a notch.
 
overheating??

so what may i ask is the solution?
also any thoughts as to the oil pressure?

much thanks

a solution is as KLP92 suggested to retard the ignition slightly --easy :) or increase the octane rating of the fuel you use---not very practical on a day to day basis :( but maybe OK for track days etc. :rock: or physically reduce the compression ratio by increasing the volume of the combustion chamber by grinding a little of the head away or using a thicker head gasket or changing the pistons--all means partly dismantling the engine again expensive.:eek:
Only other thing that comes to mind that might cause pre detonation is if your engine in running excessively hot. So check out the thermostat, radiator waterpump etc thermostat in particular, As KLP says oil pressure sounds fine.
 
Thanks Grober. i shall give that a go.
My question is, is it safe to turn the EZL switch, the handbook specfically states to leave it on 'S'?
How would i know if its running hot? Im using Mobil 1 0w40...
In traffic it creeps up to 105 degrees but goes back down again when moving.
Thermostat is new. Rad & water pump are OK too.
 
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