Technical Oil pressure and turbo boost punto gt

[nikolas12]

Guys I need you enlightment....

I recently bought a Punto gt. I have noticed a ticking noice coming from the engine's valve cover. My mechanic opened the valve cover and we found out that a cam lobe was worn. The damage was obvious with bare eyes. Also the valve adjusting disk was weared out a lot. The damage was found on the third cylinder's exhaust valve.

So, we changed the damaged adjusting disc and we checked the valve clearances and everything was ok. The noice is reduced.

My mechanic also changed the engine's oil and oil filter. We used Agip i-sync 10-40w fully synthetic oil.

Now the question comes from what i have noticed before and after the oil change.

Before the oil change, the car's oil pressure gauge during at cold start up was pointing 3,1 bar. When the oil was hot, the oil pressure dropped at 2.7 to 2,8 barv at idle.

After the oil change, at cold startup the oil pressure is 3 bar but when the oil is hot the pressure drops to 1,1 to 1.2 bar at idle.

What does this tells you?

I do not have any clear indication of what grade of oil the previous owner was using since there is no maintenace record. :bang:

Ecxept the ticking noice coming from the worn camshaft, there is no other noise coming from the engine.


Also I would like to know which is the turbo's pressure at this car. The car bone stock except a Remus Back box exhaust. My readings are 1,2 bar overboost and 0,9 constant boost.

 

[nikolas12]

I did an oil change. I moved from Agip to Castrol 10-60w. I saw improvement (aprx 1.7 bar of oil pressure at idle when oil is hot) but i still wonder if this preassure is normal.....???

 

[Steve gt]

Hi , I get a 3 bar oil pressure on start up and drops slightly once it’s warmed up , would thought you would get slightly different pressure readings depending on the viscosity of the oil , the boost pressure sounds similar to mine too , couldn’t tell you exactly as my gt is away for the winter .

 

[nikolas12]

Hi , I get a 3 bar oil pressure on start up and drops slightly once it’s warmed up , would thought you would get slightly different pressure readings depending on the viscosity of the oil , the boost pressure sounds similar to mine too , couldn’t tell you exactly as my gt is away for the winter .

Steve I would like to thank you for your reply. Although I' m a new Gt owner, I have some knowledge on engines. I'm trying to figure out if those readings are "normal" for a Gt cause I don't want to blow up my engine.

Once again thanks a lot for giving me a hint...

 

[Steve gt]

no problem , there are a few on here with gt’s too and plenty who have owned them in the past with good knowledge of them [emoji1303]

 

[nikolas12]

no problem , there are a few on here with gt’s too and plenty who have owned them in the past with good knowledge of them [emoji1303]

So let's hope they will answer????

 

[bluejohn125]

So you didn't change the camshaft, you still have a worn lobe, but you only changed the adjusting shim? This will fix the noise but the valve lift will be wrong, and this cylinder will have less performance and unbalance the engine.

I think you still have a problem with that valve, maybe it is sticking or the spring is stiff, and this gives more wear to the cam and shim. Or if you have a problem with oil delivery to the top of the engine in that area. Are there some holes in a pipe that could be blocked? This was the exact problem with the 1.4 12V version of this engine in the Brava / Bravo, blocked oil rail giving worn and noisy camshaft.

If you have low oil pressure when hot this will of course reduce the lubrication all around the engine including the top end, and the classic reason (back in the 70s / 80s when people rebuilt engines at 70,000 miles) for this was worn crankshaft main bearings. Is there any rumble from the bottom end of the engine?

The fact that you get low oil pressure with the correct oil grade (40 hot) but OK pressure with a thicker racing / high temp oil (60 hot) indicates to me that the bottom end of the engine and maybe the pump needs attention.

 

[nikolas12]

Dear John

Yes I only changed the adjusting shim. No I do not have any other noise coming from the engine. I know this is not the correct way to solve the problem but I'm going one step at the time in order to find out what is the problem. It would be a waste of money and time to change the camshaft without figuring out what caused the wear of the shim an the cam.

You see I'm dealing with two problems at the same time. The first is oil pressure and the second is wear at the cam and shim. The cause of these troubles might be the same but I still do not know this for sure. So I have to have under control the situation and try figure out what it going on.

I would be dumm If I had in mind that an oil change and a shim would solve my problem, but it's a start. I am fully aware that the engine is not running as it should but for the time being that is the only thing I can do

Anyway, the next thing to do is to change the crankshaft main bearings and the oil pump.
What I do not know yet is if it is possible to change the main bearings without dismantling the engine. Then again there would be a short period of testing. If it is possible to change the main bearings without removing the engine from the car, I will go for it. If it is not, then I will go for an engine rebuilt.

I would really like to thank you for your reply.

 

[bluejohn125]

I think you can change the piston / crank big end bearings with the engine in place but removing the sump and cylinder head, for the main bearings it will almost certainly be an engine-out job.

Have you done a compression test? This can indicate bore / ring wear, head gasket leaks or non-sealing valves (clearances too tight).

 

[bluejohn125]

Regarding the change in oil pressure readings before and after, that is strange unless the previous owner also put in thick oil to mask the problem...

 

[nikolas12]

I have not done a cylinder compression test yet. The engine runs smoothly and there is no other funny noise except the ticking cam lobe. During the weekend I drove the car for 600 khm, and when i got back home I didn't notice any oil consumption.

 

[nikolas12]

Regarding the change in oil pressure readings before and after, that is strange unless the previous owner also put in thick oil to mask the problem...

Probably you are true. The ticking cam was there. from the first time I saw the car. I asked the previous owner and he said it's a noise form the fuel injectors.....:bang::bang::bang:
I didn't buy that. I thought it would need just some valve timing....

 

[nikolas12]

I think you can change the piston / crank big end bearings with the engine in place but removing the sump and cylinder head, for the main bearings it will almost certainly be an engine-out job.

Have you done a compression test? This can indicate bore / ring wear, head gasket leaks or non-sealing valves (clearances too tight).

To 7 of the 8 valves the clearances from 40 to 45 for the intake valves and 50 to 55 for the exhaust valves.
The valve with the wor cam lobe and worn valve shim had a clearance of 110.

 

[nikolas12]

Yesterday while I was driving back home I saw a garage expertizing on Fiat/Alfa Romeo. I decided to hop in and ask a question.

The guy in charge told me that my oil pressure is fine (aprox 1,5 bar/ hot engine/idle) and he said also that the engine is in danger when oil pressure is from 1 bar and below or when the warning light on the dash board is on

Today I found the bolts of the oil pan loose:bang:...also I found out that instead of rediator fluid the car was cooling with water:bang:.....and the heater is disconnected from the water hoses:bang:

I really do not know what to assume.....

from what I can tell (starting from worst case senario)there must be...
1) worn main bearings.
2)the engine must have been rebuilded but the guy who did that must have been something else than a mechanic

 

[Steve gt]

Sounds like the engine has had a hard time , wondering if the heater matrix inside the car is leaking if it has the pipes disconnected ?

 

[nikolas12]

Sounds like the engine has had a hard time , wondering if the heater matrix inside the car is leaking if it has the pipes disconnected ?

Probably the heater matrix is leaking. I can't see any other reason that they disconnected the pipes.
I will connect them again and we will find out the reason...

 

[nikolas12]

Today I changed the water from the cooling circuit. Of course I replaced it with proper radiator fluid (the pink one). I noticed a little higher temperature when the car is stuck in traffic. A part from the idle that is kind of wired because of the worn cam lobe, I noticed a smoother operation.

Question:
Do Gts have a two scale radiator fan?
Mine works only high scale for a couple seconds and then shuts down.

 

[Steve gt]

Today I changed the water from the cooling circuit. Of course I replaced it with proper radiator fluid (the pink one). I noticed a little higher temperature when the car is stuck in traffic. A part from the idle that is kind of wired because of the worn cam lobe, I noticed a smoother operation.



Question:

Do Gts have a two scale radiator fan?

Mine works only high scale for a couple seconds and then shuts down.

My radiator fan only comes on high for a short time [emoji1303]

 

[nikolas12]

I found these from a Hyens book. Probably most of the gt owners might be familiar but I'm posting them just in case somebody (like me) needs them.

engine type:176A4.000
capacity/ cylinders:1372/4
compression ratio/pressure: 7,8 bar
oil pressure:1 bar (3,7)
oil temp: 80 oC
valve clearance-intake: 0,40 +/- 0,05 mm
valve clearance-exhaust: 0,50 +/- 0,05 mm
firing order: 1-3-2-4
thermostat opening temp: 80 oC
radiator cap pressure: 0,98 bar

according to these readings my oil pressure seems to be fine.

What really troubles me is why the cam lobe is damaged..:bang:

 

[Stefan Dieters]

Check if your head is getting enough oil. If he rebuild the block without knowing what he was doing, he might placed the gasket the other way around, realised it to late, damaged that one lobe to low oil feed, replaced the gasket the proper way.