Heavy vibration - head gasket?

[prado1 Lurker Find all posts View Profile Close prado1]

Hi,

I have a 1996 AT 3.4L petrol Prado with 125,000km on the clock - I'm no expert mechanic but I'm based out in Africa and the garages here are pretty unreliable so any help diagnosing the problem would be much appreciated.

When I am stuck in traffic, with the car still in Drive and my pedal on the break, there is a very heavy vibration which reverberates throughout the car (I think it is coming from the engine, and the 4WD stick vibrates heavily). If I put it in Park or Neutral there remains some vibration but it is substantially reduced. I've also noticed that the fuel consumption around town seems to be worse than normal, and it seems to be a bit sluggish when accelerating from a low speed.

I have had some issues with the radiator losing coolant when I take the car on long journeys (it never loses any when taking it around town, only if you drive long distances - over 200km flat out it might lose 1L), but the radiator has been pressure tested and they weren't able to find a leak anywhere. This led me to think it could be a problem with the engine (head gasket/cylinder heads). Is rough vibration a potential symptom of this? None of the other symptoms I've heard of with a gasket (oil in the coolant, milky oil) are present.

Or could the vibration be something to do with the exhaust (there is a slight rattling coming from it)? Or the throttle body?

Thank you very much in advance for your help!

Harry

[Matty80 Avid PP Poster! Find all posts View Profile Close Matty80]

Re: Heavy vibration - head gasket?

Are all your cylinders firing, being petrol - check your spark plugs for wear, check the connections of the leads, maybe a coil?
That would explain (probably) the rough idle, loss of power on acceleration and increased fuel consumption (maybe)...

EDIT: Could also be a blocked fuel nossle?

Anyone else correct me on this maybe? I'm no petrol engine expert...

[williade Avid PP Poster! Find all posts View Profile Close williade]

Re: Heavy vibration - head gasket?

I think Matty could be on the money. It sounds like its misfiring.

The rattling could be the heat shield on one of the exhaust manifolds. I think they used some kind of soft washer when they are bolted on and when the washers wear away, there is a little bit of free play that allows the shield to rattle.

Cheers,
Declan.

[Leethal Advanced Member Find all posts View Profile Close Leethal]

Re: Heavy vibration - head gasket?

From your description it is only sluggish at low rpm & "vibrates" or shakes.
If that is the case (power loss at low revs only) I would check for a vacuum leak.
Check hoses for a break or disconnected, tighen inlet manifold & plenum chambers bolts.
Make sure the inlet fittings from the air cleaner are on correctly and clamps are tight etc.

I would think if it was a head gasket or similar you would notice loss of power across the whole rev range, same with a faulty injector, spark plug or leads.
Perhaps your maf sensor is dirty (if a hot wire) or fouled/stuck (if a flap)

Just my thoughts.

Lee

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Re: Heavy vibration - head gasket?

Worn engine mounts?

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Re: Heavy vibration - head gasket?

Any update?

[Beast2h Member Find all posts View Profile Close Beast2h]

Re: Heavy vibration - head gasket?

maybe check idle speed and clean the throttle body.