Pajero Vibration

[Siddiq]

Hi All,

I recently purchased Pajero 3.0 2008 with 165k kilometers on the clock. I can feel engines vibration when in N or D and very less vibration when at P specially at cold start. I flushedchanged all the fluids and spark plugs as routine maintenance along with Engine gasket which was slightly leaked. We also checked engine and gear mounts and apparently they all look good. The RPM is 900 on Neutral and 200-300 when shift to D. I can feel the vibration at traffic signal and not while running. Can anyone pls guide me in diagnosing as I have already spent a small fortune in diagnosing

Look forward to hear back.

[derik]

Hi Siddiq,

Welcome here, I do have a notorious Pajero as well and suffered quite a few bits and bobs already. To start changing all fluid and oil was a good idea. Can you please clarify if you changed the engine head gasket or engine oil sump gasket?

btw, to get you benchmark below are the ideal RPM you should be looking when fully warm:

P: 850-900 (With AC)
P: 750-850 (Without AC)
D: 700-750 (With or without AC)

Go back and check again how much it differs (roughly), as your 200-300 seems unrealistically low, as on that RPM I think car should shut down and not in a drive-able state.

 

[Siddiq]

Thank you so much derik for your valuable input. I believe engine head gasket. Since I was changing Spark Plugs so I went for this as well in one shot. Let me check the RPM against the ones you have mentioned. Apart form that is there anything you suspect.

[derik]

OK, you don't seem to be very informative on gasket differences. Head gasket is one of the MAJOR gasket in any automobile engine, that separates the Oil and Water in the engine. It is not supposed to be leaked EVER and made and design for lifetime of the engine. If it leaks there must be some reason for that and one of the major reason is overheating that overheats the engine and literally spoil this gasket and engine oil and water (coolant) get missed. It is a very big job to open the engine head and if it's not done professionally then engine will run rough through out its life.

So more than anything., you 100% find out if engine head gasket has changed or not? Send some engine close up pictures (without plastic cover) and I can tell you if its changed or not (75% surely).

[ethan]

Just to help solve the puzzle:

• Head gasket is fixed from top of the engine bay.
• Engine sump gasket is fixed from bottom of the car.

[treks]

Hi Siddiq,

The problem you are having with your Pajero has nothing to with any gasket. The low idling speed that causes the vibration happens because the step-up actuator does not work.

The device works on the trottle, and it increases the idling speed when you put a vehicle in gear. When you put an automatic vehicle in gear, the transmission engages, which reduces the idling speed due to the drag of the transmission, so the transmission sends a signal to the step-up actuator to say that it is now in gear, and it must increase the idling speed to counter-act the drag the transmision places on the engine. 

When you drive at higher speeds, the engine overcomes the drag of the transmission, which is why you don't notice the vibration at high engine speeds. Remember that N and P is not the same thing, because different parts of the transmission is disengaged in N and P. When the  transmission is in P, the fluid in the transmission follows a different route through the transmission that causes less drag than when the transmission is in N, so you will notice a difference in how the engine idles when it is cold, and in P.

The step-up actuator also works on a signal from the AC, so it is possible that the circuit from the transmission to the actuator does not work, while the circuit from the AC compressor might work, which is why you don't get the slow idling and vibration when you turn on the AC. 

I suggest that you take the vehicle for a full OBD II diagnostic check to confirm that the circuit from the transmission to the step-up actuator is defective. It is very difficult to test this circuit yourself, since you don't know what the electrical  values on the testing points should be.

There might be some power in the circuit, but a high resistance because of bad connections, or a defective switch, so have this circuit checked out with a diagnostic computer.  

 

 

 

[Siddiq]

Thank you guys. That was quite informative. I came across one article that was mentioning Timing belt tensioner could be one of the cause. However I checked with previous owner and he said that he changed timing belt at 130k now its 165k. However let me go back and check the RPM thing and I will share the readings meanwhile.

[derik]

I wait for those reading and gasket answer, reason being if it's a head gasket then I will definitely suspect the timing belt timing is not correctly positioned or few other things to doubt like missing vacuum hoses, wrongly placed intake manifold gasket can also cause this rough idling and plus what treks mentioned is also one of the possibility.

Just to put two and two together, from how long you had this Pajero? And was it been like this since your purchase or after the repair you got? And find out exactly which gasket has been changed?

Btw, Pajero timing belt has to be changed at 100k and not 135k, so definitely the previous owner has already contributed to some extent to the present condition. 

 

[treks]

Hi Guys,

Just to clarify- If the timing belt was the problem, in that the valve timing is incorrect, the engine would run rough the whole time. It would not run well in N and then start running rough when the car is put into gear.

Incorrect valve timing stays incorect until someone fixes it- it does not cause problems that come and go.

[Siddiq]

Hi,

Actually I changed spark plugs along with its 6 spark plug gaskets and both the head gas kit (from Top). The vibration was there before the gasket changed and at the time of purchase. Apart from that the car is in excellent condition when it comes to interior ,exterior and engine performance.

Below are the RPM reading noted after driving 40 kms.

P : 800 (without AC)

N : 800 (without AC)
D: 500-800 (Without AC)

I can feel the vibration in all the above 3 states.