Ask Xulfiqar - An Automotive Encyclopedia

[anon36782927]

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[cracked1]

There is no vacuum leak. Total fuel trim remains close to 0 and fluctuate between -3 to +3. Any leak would cause fuel trim to go bananas right?

[capsat]

Karachi saeed manzil next to longman rubber parts shop. mama parsi girls school is another land mark for it the number is shared correctly

[cracked1]

The issue has been resolved by myself, alhamdulillah. Issue was the IAC rotating portion, was slightly bent. Straightened it and voila, issue settled.

The potion that my finger is touching, a slight metal piece extends, that was bent a little.

[overspeed111]

diesel engine oil is better than gasoline engine oil
using 20W50 Carient on my stock engine khyber G10a heard about diesel engine oil will perform better on old engine with longer oil change intervals currently changing at 2500 as one mechanic told me that its crank is a bit noisy go for a overhaul maybe he want to make quick bucks or he is true as i didn't heard heavy noise from engine its just tuk tuk noise from tappets and a little grr noise at high RPM i am confused what to do please help
other than that engine runs absolutely fine no oil consumption or anything engine heat goes up on CNG but on petrol its fine

[rajaahmed96]

Use delo gold 15W40 it will be fine for your car. Change it at every 3000kms.

[capsat]

using 20W50 Carient on my stock engine khyber G10a

perform compression test please if the readings wet / dry are above 160 psi change oil filter and switch to 10W-40 oil of any brand from brand owner station. change interval shall be 6000+ kms

anything engine heat goes up on CNG

please flush clean the cooling system check for thermostat valve in system and change radiator cap. Make sure the cooling fans are running automatic.

[overspeed111]

i think delo gold is from Caltex is that available in 3LTR Packing?
but my question remain unanswered, is Diesel engine oil better than gasoline engine oil for an old overhauled engine to make it last longer? any other issues come up with this experiment?

[overspeed111]

if the compression test is below 160 psi what to do then ? stick to this oil 20W-50 or start using Diesel engine oil 15W-40 or still go for 10W-40? after all its an old engine doesn't like too much experiments and overhaul cost a lot.

2 times flushed complete cooling system and one time with soap water earlier using Osaka Coolant (Green one) then again flushed with soap water and now using Guard coolant (Red one) its more than 6 months ago, i will again do this procedure and now use some different coolant which one please suggest.
in the meanwhile i've changed water pump and fan belt as well, fan is direct and no T-stat as engine was overheating on CNG but remain normal on petrol, before flushing its overheating on both fuels i don't understand what is causing this as even radiator looks new (Aluminum radiator with plastic housing)
Thank you for suggestion

[capsat]

if the compression test is below 160 psi what to do then

if values are under 160 psi plan an engine overhaul. parts are available oem new.

digits before W in oil classification signify ambient outside temperature as in cold start.
so oil grade with xW-50 is FAT then xW-40 which is FATTER then xW-30. That means when outside temperature is 10C the 50 grade oil will be slower to move and lubricate parts then 40 grade and faster to lubricate will be grade 30 oil.

the difference between diesel engine oil & gasoline engine oil is ZDDP / CST and detergent properties. Diesel engine oils can be used in petrol engines but not vice versa.

fan is direct and no T-stat

when you overhaul the engine please re wire fans to work automatic and add thermo stat valve to the engine. Use caltex permix coolant for every vehicle under your usage.

there is a reason for thermostat valve in the engine, and fans to work at certain temperature.

your mechanic is not an engine designer neither he is able to use a torque wrench at his workshop. Always use your educated skills to guide your mechanic to work as you ask, not as he suggest. Please

[overspeed111]

Thank you

[gohar83]

Is there a possibility of a bad crank pulley causing this slight overheating ? 1HD FTE
@Xulfiqar

[Xulfiqar]

Yes

It’s possible

But first make sure your fan clutch is good, coolant mix is not more than 50% and radiator fins are clean

[gohar83]

• Apparently the fan clutch looks ok to me. It was refilled back in sept'18 with toyota's 10,000cst oil and doesn't move freely with hand.
• Radiator was also cleaned (though it wasn't needed) because its running on coolant since day 1
• Coolant to water mix is 50/50.

Now should i refill the fan clutch again ? Maybe there's a problem with the BMS. Or should I replace the fan clutch assy with a brand new one ?

Is there a proper way to test the fan clutch?

[Xulfiqar]

does the fan roar when the temperature rises?

its very obvious.

[gohar83]

yes I can clearly hear that roar above 2200 rpm.
at idle its very quite when fully warmed up.

[Xulfiqar]

does it ever roar when the engine warms up? - you can test it with a rolled up newspaper when the engine is very hot - I usually can do a visual test (as Ive experienced it thousands of times) - the fan should follow the engine speed if the clutch is locked on and it will be deafeningly loud too. - At this moment of time you can kill the engine and see if the fan stops almost immediately (within 5 turns) proving that the clutch was locked on

If it freewheels to a stop on a very hot engine then you have an issue. The issue can be

1 - empty or low silicone oil in clutch
2 - bad BMS on clutch
3 - missing air shroud
4 - cold spot in radiator infront of fan clutch

The newspaper test is to use the roll gently on the fan blades to stop them, if you are able to stop the fan with the newspaper roll then the clutch is off (freewheeling) - if the fan is locked on - it will snatch the roll and shred it. (you can use a roll of cardboard too - be very careful with this test.

In professional environments we put a mark on one fan blade and a strobe light to see the mark on the fan. We accelerate the engine to see the fan rpm change on a working clutch (this is done as a fool proof verifiable cause/effect repair)

[gohar83]

@Xulfiqar
above 2000 rpm the roar can be heard clearly even when sitting inside(all windows/doors closed). below that rpm its quite even when the engine is very hot

whenever i kill the engine (whether its fully warmed up or cold) the fan stops immediately within 1 turn.

and it doesn't spins more than a 1/4 turn when i try to rotate it with hand (engine warmed up/turned off)

fan shroud is in place. t-valve was also replaced 5000 kms ago.
only the radiator cap is still the factory one. (make: 2000, mileage: 192,000kms ) should I replace it ?

[1mran]

Change interval of 6000+ prompted me to respond,
I have 2004- Mehran, it's 110k driven after engine overhaul -- I use Mobil 10w40 engine oil and change after 3000 kms -- do I change too early?

Let me also take the opportunity to ask couple of questions:
1) After 2000 km, Oil decreases @1/2 liters --what to check?
2) water+ black smoke comes from the pipe when I rev up the engine -- something to do with carburetor?

Regards.

[399.ak]

Change interval of 6000+ prompted me to respond,I have 2004- Mehran, it's 110k driven after engine overhaul -- I use Mobil 10w40 engine oil and change after 3000 kms -- do I change too early?

6000+ interval is mostly for cars with oil capacity of around 4L running with good 5w-30 semi/fully synthetic oil and good filters.
So for overhauled mehran which oil is like 2.7L and require 10w-40 oil max you can go is 4k km.

After 2000 km, Oil decreases @1/2 liters --what to check?

Maybe overhauling was done properly 90% chance in
Pakistan so people prefer swaps. Otherwise just top it up it's no big deal. Old engine or even many new ones tend to reduce little oil like 200-300ml after 2-3k km.

water+ black smoke comes from the pipe when I rev up the engine -- something to do with carburetor?

Regards.

Black smoke means it's running rich, more petrol.
There is a small mixture pin in carburetor just check it. Maybe it need cleaning or replacement.

.