tappet adjustment gone wrong?

[john_d]

A few days back I had the timing belt and bearing replaced in my PZJ70. They also did tappet adjustment at the Toyota garage.

However, since the tappet adjustment I had been hearing a thumping noise while the engine runs. Today I showed the vehicle to an experienced mechanic in another garage. He opened up the air filter box while the engine was running and that thumping noise seemed to be emanting from the air filter box. He concluded from this, that the valve clearence on the intake valve was to high and that combustible gas was being pushed back through it into the air filer box during combustion.

Is this the correct diagnosis and can this conditon damage the engine?

Apart from tappet adjustment what other procedures constitute engine tuning? And what things should I keep in mind when I tune the engine?

Thanks

 

[Ron R]

A few days back I had the timing belt and bearing replaced in my PZJ70. They also did tappet adjustment at the Toyota garage.

However, since the tappet adjustment I had been hearing a thumping noise while the engine runs. Today I showed the vehicle to an experienced mechanic in another garage. He opened up the air filter box while the engine was running and that thumping noise seemed to be emanting from the air filter box. He concluded from this, that the valve clearence on the intake valve was to high and that combustible gas was being pushed back through it into the air filer box during combustion.

Or you have misunderstood what he was saying or he is telling BS.

Too much clearence will cause the valves to open too little (As far as you can say that when talking about distances of tenth's or hundred's of millimeters)

But that he is even saying that the combustion gas was being pushed back.... go look for a more experienced guy.

Is this the correct diagnosis and can this conditon damage the engine?

I don't think this is the correct diagnosis.
I'm afraid the timing belt has not been installed correctly but one (ore more) tooth off.
This could damage the engine in a costly way, but obviously you're getting away with it.
My advise is, if you have to drive it, don't rev it too much untill you're fully sure the timing belt is poperly fitted.

If they indeed fitted the TB in a wrong position I hope they did a better job setting the valve clearence.

Apart from tappet adjustment what other procedures constitute engine tuning? And what things should I keep in mind when I tune the engine?

Thanks

If you're just talking about tuning it's a matter of setting everything to specs (timing - fuel - clearences ) and replacing/repairing the parts that get worn (sparkplugs - injectors - filters)
If you're talking about getting more than stadard power out of and engine, then you can go as far as you like, from polishing the in- and outlets, adding turbo(s), wider exhaust to different engine management system and so on.
In that case your imagination or purse (whatever comes fist;p;p) is the limiting factor.

Have fun

 

[john_d]

If in fact the toyota garage has installed the wrong timing belt what damage could the engine incur?

What is the correct part no. of PZJ70 timing belt?

Thanks.

 

[roscoFJ73]

If in fact the toyota garage has installed the wrong timing belt what damage could the engine incur?

What is the correct part no. of PZJ70 timing belt?

Thanks.

A wrong or incorrectly fitted belt can open the valves at the same time the pistons are coming up
But this hasnt happened.Its more likely opening or closing valves too late/early.

This is what it looks like ,the 1KZ 1HZ 1PZ and 1HD T are all much the same in the belt dept.
Dont go by those timing marks,they maybe different to your 1PZ

If you check it ,you should have the top one (CA) as in the pic and the IP mark should be aligned with a mark on the pump pulley(IP) aligning itself with a mark on the alloy timing case.The 1HZ 1PZ manual shows it being roughly where the 1KZ T mark is on this diagram.

If it doesnt look right ,I would not recommend trying to fix it without a manual in front of you

There is 3 clips and 3 screws holding the plastic cover on

Its a 1/2 hour job to do it yourself and is easy and worth learning

 

[john_d]

i've had the timing belt checked by an experienced mechanic. The notches line up. So, it seems that there's nothing wrong with the timing belt. He claims that it's because of a leaking intake valve.

However, two different mechanics, and both of them tell me that sometimes, after tappet adjustment it is not unusual for valves to leak for a while. They say that after about the 1000 kms the valve could adjust itself (shut itself properly) and the irritating thumping noise could gradually die down. Is all of this possible?

Thanks.

 

[Ron R]

John,
excuse me but I don't buy that 'leaking for a while' story. I leaking valve could be the culprit but with the clearences properly set, this would mean there is a valve job to be done.

The most worrying was the timingbelt. But that obviously is fitted correctly.

There might be an other, very simple explanation for the - to you - unusual sound.
If you look at the airduct in between the filter and engine there is a box connected to this duct. This is a kind of resonance box. At the connectionpoint (where it connects to the airduct) there will be a marking.
Try an play around with moving the box - a little at the time - in and out the duct in the area of that mark.
This alters the sound slightly maybe that had shifted during the maintenance or the airduct has been put back in place in a slightly different position.

 

[70sguy]

If one intake valve is not sealing it will show up on a compresion test, so consider doing that. For good measure I would recheck the valve shims that were installed to bring the clearances in line. If a puck was swapped in that is slighly too thick it will cause the valve to not seal as it should.
I could see where a mechanic might swap a shim in that is close but not 100% to get the job done and out of his hair. They are not wrench and screwdriver adjustable like B and H series engines. So to do these things right you really should first go in and take carefull clearance measurements and Mic the shims on the valves that are out of spec. Then use the chart in the Engine manual to order up the required shims and to be safe, at least one shim on either side of the shim you need. Then go in again and swap shims to hopefully get right on spec.
Correct valve clearances really brings cylinder compression closer together on these motors and make a really big difference in how smoothly 1HD-T and 1HZ engines run.
Good luck.

 

[john_d]

I've tried adjusting the resonance box but the thumping noise persists. However, what is the orientation of the resonance box? With the letterings of the box facing the ground or the sky?

I've had the valve clearance adjustments done twice in the toyota garage and had them rechecked by an experienced mechanice in another. To them it seems okay.

According to the Toyota garage, during it's 17 yrs and 153,000 kms on the road, this vehicle had never had it's tappets adjusted(before now). 9 of the 10 shims were changed. Could this have led to unusual valve wear and hence the resultant valve leakage?

The compression of the 1Pz engine is meant to be between 27kgcm2 - 37kgcm2, with a maximum difference of 5kgcm2 between cylinders.

When I performed the tests, after the tappet adjustment, the results were as follows:

cyl 1- 32kgcm2
cyl 2- 32kgcm2
cyl 3- 32kgcm2
cyl 4- 32kgcm2
cyl 5- 30kgcm2

Could cylinder 5 be the culprit?

We have very poor quality of diesel in my country. Since the price of kerosene is subsidised and substantially lower than that of diesel, kerosene is routinely mixed in the diesel. In light of the above, I've been advised by experienced mechanics to mix between 1/2-1 ltr of engine oil for every tank full (85ltrs) of diesel. This, they claim will prolong fuel pump and engine life? Is this the case? And if so, what should the ratio of engine oil and fuel be?

Thanks.

 

[roscoFJ73]

I've tried adjusting the resonance box but the thumping noise persists. However, what is the orientation of the resonance box? With the letterings of the box facing the ground or the sky?

I've had the valve clearance adjustments done twice in the toyota garage and had them rechecked by an experienced mechanice in another. To them it seems okay.

According to the Toyota garage, during it's 17 yrs and 153,000 kms on the road, this vehicle had never had it's tappets adjusted(before now). 9 of the 10 shims were changed. Could this have led to unusual valve wear and hence the resultant valve leakage?

The compression of the 1Pz engine is meant to be between 27kgcm2 - 37kgcm2, with a maximum difference of 5kgcm2 between cylinders.

When I performed the tests, after the tappet adjustment, the results were as follows:

cyl 1- 32kgcm2
cyl 2- 32kgcm2
cyl 3- 32kgcm2
cyl 4- 32kgcm2
cyl 5- 30kgcm2

Could cylinder 5 be the culprit?

We have very poor quality of diesel in my country. Since the price of kerosene is subsidised and substantially lower than that of diesel, kerosene is routinely mixed in the diesel. In light of the above, I've been advised by experienced mechanics to mix between 1/2-1 ltr of engine oil for every tank full (85ltrs) of diesel. This, they claim will prolong fuel pump and engine life? Is this the case? And if so, what should the ratio of engine oil and fuel be?

Thanks.

Your compression is good with them all being well within the 10% variation allowed.
If one was bad and leaking it would much lower than the others.



Normally you would use a proper additive with a lubricity agent although I cant see anything fundamentally wrong with the engine oil.
Ive been advised to use ATF by mechanics. With these home remedies ,its difficult to know how good and how much to use but I guess a about a litre wouldnt be too far off

 

[70sguy]

If you want to add something to simply add lubricant to the fuel I would try using a good quality 2 stroke motor oil. It's a popular thing among the VW diesel crowd. The logic is that you are adding something that is actually designed to lubricate and then burn within an internal combustion engine.

 

[Ron R]

If you want to add something to simply add lubricant to the fuel I would try using a good quality 2 stroke motor oil. It's a popular thing among the VW diesel crowd. The logic is that you are adding something that is actually designed to lubricate and then burn within an internal combustion engine.

X2

John_d:
I've tried adjusting the resonance box but the thumping noise persists. However, what is the orientation of the resonance box? With the letterings of the box facing the ground or the sky?

That doesn't matter. Have it the way it looks the nicest;p

In my rig there is only one way I can do this. The other way around it won't fit because of it's shape.

 

[john_d]

Could the thumping noise be normal with the 1Pz?

My radiator is leaking slightly. How could it be repaired?

Assuming the temperature gauge is working properly, at what point, between C and H does the needle normally hover? And if the needle exceeds the half way point, does it point to some cooling issues and could the engine be damaged?

lastly, some of my friends tell me that it's important to drive a diesel vehicle at high revs to avoid carbon deposits in the cylinder. As this is my first diesel, what driving style should I adopt to prolong engine life?

Thanks.

 

[Ron R]

Could the thumping noise be normal with the 1Pz?

It was my understanding that the noise changed after the valve clearence was set...
A kind of thumping noise might be normal for your rig. Sometimes a certain rig has a certain 'sound'

My radiator is leaking slightly. How could it be repaired?

Hmmm, AFAIK your radiator is fully metal....so some soldering could do the job.

Assuming the temperature gauge is working properly, at what point, between C and H does the needle normally hover? And if the needle exceeds the half way point, does it point to some cooling issues and could the engine be damaged?

Can't say much to this. Indications can vary from rig to rig. Just get used to what the needle indicates under normal conditions, that is, normal driving no towing under city and freeway conditions at average temperatures for your area. Then, later on, compare this to the actual indication of the needle.
Dunno for your rig but the temp-needle in my rig is always hammered to a certain position. This because Toyota uses a trick to stabilize the needle-indication. Only during extreme conditions the needle will move like when I was in the desert winching myself clear of a dunevalley for about two hours under +35 deg C.

lastly, some of my friends tell me that it's important to drive a diesel vehicle at high revs to avoid carbon deposits in the cylinder. As this is my first diesel, what driving style should I adopt to prolong engine life?

Thanks.

Start slowly. Give the engine time to get to it's operating temps before getting to it. To my opinion this is at least ten minutes after the temp indicator has reached it's normal position.
If you obey this rule there is hardly anything you can do wrong with it as long as temps are within limits.
I myself never drive with high rev's, except the occasional exception. Under normal conditions I will not exceed 2800-3000 (redline is 4400) RPM. But then, I have a 1HZ and this engine differs from your's.
This engine was recently tested (I wanted to know it's condition) and despite having 230K km's of which I did a lot of towing (1600kgs trailer) and a lot of off-roading, the engine performed to standard. No abormal oil consumption, wich means about 3/4 ltr during 7500 km's.
So I never have to add any oil as my service-intervals are at 7500 km.

 

[roscoFJ73]

With the 1PZ being a 5 cyl ,do 2 pistons fire at the same time? Some 5 cyl engines are designed so the 5th cyl fires between the other cyls combustion strokes to make them run smoother.

 

[roscoFJ73]

lastly, some of my friends tell me that it's important to drive a diesel vehicle at high revs to avoid carbon deposits in the cylinder. As this is my first diesel, what driving style should I adopt to prolong engine life?

Thanks.

They shouldnt get a lot of carbon deposits if the injectors are good. The 1PZ/HZ are a relatively clean diesel.
I keep mine in the 2300-2800 range either in 4th or 5th.

Diesel tend to last longer at lower rpms but these engines were designed to rev higher than their predecessors