suspected cylinder and head problem?

[scooter32 Lurker Find all posts View Profile Close scooter32]

Hi guys first time to this site,

just to note i am not overly mechanical now the basics that about all.

I recently purchased a 1996 v6 prado, the other day it started to shunter a little on idle, the higher the revs the less vibration occurred. I took it to a mechanic today to receive the worst possible news. that after changing the spark plugs he found that the rear passenger side plug was fouled up.
he basically said to expect the worse a new head and up wards from that. he said a new head can range from $1700.00 upwards plus labour plus any additional parts water pump etc..... so I'm thinking i would need to allow 5g.

what are my options considering an engine swap at a toytoa wreckers as 5g is not really an option at this stage.

what are peoples thoughts and as i live in adelaide can anyone recommend an engine swap place.

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

Did he actually confirm major engine failure such as cracked or warped head? It could just be head gasket. What is the condition of the engine oil and coolant - ie any traces of mixing occurring?

Low RPM misfire is also often caused by moist or corroded ignition lead contacts. Easy thing to clean or replace.

Additionally if work is done on the engine and the water pump is included, do the timing belt as well and consider it your 150,000 km service which costs in excess of $1,000 anyway.

Engine replacements always come with hidden issues, I wouldn't recommend it unless absolutely warranted.

[scooter32 Lurker Find all posts View Profile Close scooter32]

Did he actually confirm major engine failure such as cracked or warped head? It could just be head gasket. What is the condition of the engine oil and coolant - ie any traces of mixing occurring?

Low RPM misfire is also often caused by moist or corroded ignition lead contacts. Easy thing to clean or replace.

Additionally if work is done on the engine and the water pump is included, do the timing belt as well and consider it your 150,000 km service which costs in excess of $1,000 anyway.

Engine replacements always come with hidden issues, I wouldn't recommend it unless absolutely warranted.

Thanks for the info, no there is no confirmation of cracked head and no mixing of the coolent and oil etc , he just showed me the oiled up spark plug ad said he had great difficultly removing it, and it now running as bad if not worse than before, but i drove it home 30kms and when up to speed e.g. 80kms feels fine. maybe a second option is needed.

[VL400 Member Find all posts View Profile Close VL400]

When trying to find the very minor coolant loss from the overflow bottle I noticed a very small water leak at the rear of the motor near where the heater pipe disappears under the intake manifold. Also had a very minor rough idle/hesitation just as the motor would start when cold, worse after sitting for a few days.

But the real shock was when pulling the spark plugs, a couple on the drivers side were pink! Red Toyota coolant…

The lower intake manifold gaskets were shot, there is a coolant bridge linking the banks of the engine. The rear and front cyl had water getting in to the intake ports. Replaced with genuine Toyota and has been running better than ever, idle was much smoother as a bonus! Hadnt really noticed the slightly rough idle as it was gradual.

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

Oiled up spark plug doesn't sound like a head problem, I would think more likely a piston ring issue or possibly a valve stem seal.
Did they do a cyl compression check? Try letting the engine idle for a couple of minutes then give it a rev, if a valve stem seal is leaking usually you will see oil smoke out the exhaust.

As the ignition system on the 3.4 is a lost spark (plugs fire in pairs) if one plug can't fire the partner plug may not spark properly as well, this may cause 2 cylinders dropping out at idle.

Definitely have more diagnostic work done before committing to a course of action.

lee

[Turbo Piston Senior Member Find all posts View Profile Close Turbo Piston]

I think you should get a second opinion!

[Danda Senior Member Find all posts View Profile Close Danda]

Oiled up spark plug doesn't sound like a head problem, I would think more likely a piston ring issue or possibly a valve stem seal.
Did they do a cyl compression check? Try letting the engine idle for a couple of minutes then give it a rev, if a valve stem seal is leaking usually you will see oil smoke out the exhaust.

As the ignition system on the 3.4 is a lost spark (plugs fire in pairs) if one plug can't fire the partner plug may not spark properly as well, this may cause 2 cylinders dropping out at idle.

Definitely have more diagnostic work done before committing to a course of action.

lee

I remember when my head went the most noticeable sign was clouds of white smoke when I started it up it was unmistakable (and expensive !!!)

[scooter32 Lurker Find all posts View Profile Close scooter32]

Thanks guys for all the info, will definitely be getting a second opion was so disappointed the other day but am holding out a little hope now lol.

[scooter32 Lurker Find all posts View Profile Close scooter32]

What I did forget to mention is that it's on lpg and the mechanic said these motors were the worst possibly engines to put gas on in relation to the valves I'd this the case?

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

Oil smoke tends to be blue in colour and has a distinctive smell.

LPG is hard on valves and one usually has to have hardened valve seats fitted.
Running an upper cyl lube will help a bit, but if you are keeping the LPG I would probably overhaul the cyl heads and at that time set them up for LPG.

But again as had been said have another diagnosis done before committing to spending a lot of dollars.

lee