[tsnyders]

Recently, I purchased a 1994 Pajero 3.0 LWB with a mileage of 278,000km but the engine had been almost rebuilt 20,000km ago - new pistons, bearings, rings and the head gasket replaced. I have also just replaced the exhaust for a s/steel one + had the unichip tuned correctly - the motor run smoothly on my last trip through Eastern Cape and Karoo - about 4,000km in total including a fair amount of off-roading

When I had the unichip tuned, the mechanic mentioned that he couldn't get one of the valves to run 'quietly' and suspected a burnt valve to be the cause. Due to the timing, I couldn't delay my first trip which, as mentioned, went smoothly.

Now, on cold start-up, the motor idles all over the place (300 - 900rpm) and occassionally stalls. Once warm, the motor runs smoothly again.

So my question is: does this sound iike a burnt valve, given that I am not seeing any smoke coming from the exhaust and am not consuming any oil?

Please advie soonest as I have a Kalahari / Namibian trip coming up next month and need to get this sorted ASAP.

Thanks

[4ePikanini]

The new advanced techies should be able to feed a tiny camera (endoscope) through the intake into the cylinder to have a look.

[4ePajero]

When I had the unichip tuned, the mechanic mentioned that he couldn't get one of the valves to run 'quietly' and suspected a burnt valve to be the cause.

A burned valve does not make a noise. I think the noisy 'valve' is the V6 mating call (ticking lifters).

Now, on cold start-up, the motor idles all over the place (300 - 900rpm) and occassionally stalls. Once warm, the motor runs smoothly again.

MAF or other cold condition sensor is playing up.

So my question is: does this sound iike a burnt valve, given that I am not seeing any smoke coming from the exhaust and am not consuming any oil?

A simple wet-dry compression test will exclude/confirm leaking valve(s).

[tsnyders]

Thanks for the advice
I performed a wet/dry test today but IMO all looks OK - the reading were as follows:
Cylinder 1: 100 psi
Cylinder 2: 90 psi
Cylinder 3: 95 psi
Cylinder 4: 80 psi
Cylinder 5: 100 psi
Cylinder 6: 90 psi

Based on the readings, cylinder 4 looked marginally low so performed the wet test - the reading went to 90 / 95 psi. Would this indicate that the valves on this cylinder possible are faulty, or should I accept that this appears OK, and look elsewhere, such as:
1. Replace all leads
2. Replace all plugs
3. Replace rotor and distributor cap.

BTW - rather a tight fit for my size hands tom get the plugs in and out + fitting the compression tester

[4ePikanini]

be glad you have the 3.0. All the other mitsu V6's will cost you a day's work to do a compression test.

[4ePajero]

Cyl #4 looks dodgy.

What were the 'wet' values for the other cylinders?

[tsnyders]

Decided to re-test all cylinders as was not convinced that the compression test was 100% accurate - also added tome Wynns product to the oil to try to 'clean' up some of the valves - so a re-test was in order. The results were as follows (note: 1st reading is dry, 2nd is wet):
Cylinder 1: 130psi / 130psi
Cylinder 2: 80psi / 105psi
Cylinder 3: 120psi / 135psi
Cylinder 4: 50psi / 70psi
Cylinder 5: 120psi / 150psi
Cylinder 6: 120psi / 150psi

So, it looks as though there is definitely a problem with cylinders 2 and 4. My impression is that it is likely to be a blown gasket, rather than burnt valves. Is this correct? As always, any advice is gladly taken.

Now, it obviously needs to go in for some rework - can anyone recommend a good workshop that will be able to do the work at a reasonable cost? I live in Cape Town, Southern Suburbs.

[4ePikanini]

based on that the heads will have to come off anyway so take them off and have a decent look. Based on the findings you can proceed further.

[tsnyders]

I have been given various quotes today, but the average for reworking the head seems to be around R15k - R20k. Thinking I should maybe just pick up a reconditioned motor and save myself loads of headaches!

Does anyone know whether I could put the 3500 motor in, connected to the current gearbox? What other mods would I need to make?

Time is of the essence as my Namibian trip looms ever closer - 3 weeks and counting!

[tsnyders]

Turns out it was 3 faulty exhaust valves on cylinders 1, 3 and 5. Took heads off (myself), sent them into the machine shop to replace and pressure test heads. All done, with no other problems reported.

BUT......

after assembly, the engine turns over, spark is there, fuel is getting through - not starting. So, I thought timing was out by 180 - took off timing belt, advanced crank by 180 and re-assembled.

Still the same problem - not starting

Anyone out there with some advice on what to check for next - or some solution to rectify this?