Tappet question - 4Y

[hoennerlouw]

Hi,

I have a 4Y engine. Previous owner said that engine was overhauled. When I start the motor there is a cluck-cluck sound which people have told me could be tappets that need to be set, however after a while (about 5 minutes) the sound disappears. My dad said he would have a look at it but we couldn't find the adjusting screws to set the tappets.

First of all, is this something to do with the tappets?
Secondly, where are the adjusting screws??

Thanks in advance
Pieter

[Riceburner]

No adjusting screws, thats normal for a 4y but if the sound is excesive the hydraulic lifters needs to be replaced and use decent oil like Delo 400.

[Mr_B]

Hi there,

First of all a 4Y does not have adjustable tappets as RiceBurner says. The 4Y is a push-rod engine, with hydraulic lifters.
Under the 'tappet cover'(yes I know it has not got tappets)... is a rocker shaft(like the middle pin of a see-saw)...
one side of each rocker has a push rod below and the other side has a valve below, like the two sides of a see-saw.
A cam follower(hydraulic lifter) sits above each cam lobe, above the cam follower is the push rod.
The lobe of the cam push on the cam follower, the cam follower pushes up the pushrod, the pushrod pushes up the rocker(see-saw arm), and in turn the valve is pressed down(opens).

The image below will help:

Pushrod Principle - but with adjustable tappets


Hydraulic Lifter running on cam lobe:


So the 4Y uses both these principles, it's a pushrod engine, but instead of adjustable tappets, it has hydraulic lifters which are 'auto-adjusted' via oil pressure.


So where does all the play(noise) come from??

1. worn pushrod - the pushrod is physically shorter than it's minimum.
2. worn rocker - the point where the pushrod sits on rocker is eaten away to much
3. worn cam follower(bucket) - on either side, where the cam lobe runs or where the push rod sits
4. worn cam lobe - the top lobe of the cam is worn down
5. cut/warm cam - the cam is cut like a brospeed cam
6. worn rocker shaft - play between the rocker itself and the shaft it tilts on

In an older engine the noise/play is usually from a combination of the above.

Remember when your engine is cold(starting in the morning), the oil is thick. It doesn't travel through the engine to easily, as the engine warms up, so the oil pressure rises and the hydraulic pressure in the lifters rises, so taking up the play where 'tappet' noise emminates from, and the noise vanishes...

When i rebuilt my motor, the mechanics use a second hand shaft, complete worn, needless to say I thought one or two of the hydraulic lifter were stuffed. After some investigation i found the rocker assembly was stuffed and replaced it, problem solved.

I wouldn't worry about it to much, especially if the engine has a warm/cut cam. If the noise is excessive you may have to investigate the parts, which is not too difficult, because the rocker and pushrods can be accessed via the tappet cover. Getting the cam followers and cam out is a bit more of a pain!

Bretton

[Scooter]

Nice Bretton.

I had typed a whole reply for Pieter only to find that you beat me to it.

The only thing I have to add to you explanation is that with hydraulic lifters the oils pressure falls as the vehicle stands. This is generally why you will only hear the noise for a short while after starting the engine.

While this is not a conclusive way of telling if it is the lifters or others parts, it normally means the lifters are losing their pressures and should be checked and replaced.

[Mr_B]

u win some you loose some hey

[Tonto]

I had the same problem. Mine was only one of the lifters (second from back) which also influenced the performance. I noticed the spark plug was quite sooty on that cylinder.
If all the lifters are noisy at startup, I would look at worn
After some investigation, I found that the lifters were replaced after a rebuilt with pirates. I got some huge quotes for replacing them but after a R 350.00 quote from the Stealers for the labour, I realized it could not be a big job. 8 new original Toyota lifters cost me R 2000.00 (after some negotiation) and I did the job myself (2 hours and a lot of fun).
Tonto now runs like a sowing machine and the power is back up.

[Mr_B]

Yip Tonto, if the rocker assembly parts(lifters, puchrods, rocker arms) are worn too much or faulty(lifters) the hydraulic pressure will no longer be enough, then the valve lift will no longer be within spec and engine performance will suffer.

The pirate lifter are known to give hassles from time to time, the engine builder guys told me they often get sets where 1 of the 4(oops 8, 2 valves per cylinder) is faulty... IMHO I will build my next engine myself and make sure things are done right

B

[Irishman]

I also have a slight clatter first start in the morning. Riceburner tell me more about that oil you recommend, and where do you get it please
Ron.

[hoennerlouw]

Thanks for the great answers

[Scooter]

Prices for interest sake: (Prices may vary from dealership)

Lifters R310 each
Pushrods R130 each
Rocker Arms R194 each
Camshaft R2537

[Hoppy]

Do not mistake piston slap for "tappet noise", the 4y motor is actually a stroked 3y, to get sutch a long stroke into a short block they had to use a short piston skirt and the conrods turn at an excesive angle, this exellerates wear on the piston skirt, on start up it will clatter, but the piston heats up and expands within a few minutes and the clatter stops.
Some cheap pistons tend to clatter after only a few thousand k's or some engineering shops rebore it to maximum tollerance, this will also cause the clatter.

[Dadz Toy BFI]

Hi,

I have a 4Y engine. Previous owner said that engine was overhauled. When I start the motor there is a cluck-cluck sound which people have told me could be tappets that need to be set, however after a while (about 5 minutes) the sound disappears. My dad said he would have a look at it but we couldn't find the adjusting screws to set the tappets.

First of all, is this something to do with the tappets?
Secondly, where are the adjusting screws??

Thanks in advance
Pieter

Pieter

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[Mud Dog]

Hydraulic lifters look pretty much the same a solid lifters except that you can see it's made up of two main parts, the body and the plunger which fits inside the hollow body and is held in with a retainer clip. The plunger is not loose inside the body but has a pre-loaded spring inside that keeps the plunger in the "extended" position (up to the retainer clip). These springs are quite hard. The body has a filler hole (usually on the side) that allows the lifter to fill with oil pressure from the oil gallery. The oil can escape through a control valve or smaller hole in the plunger where the push-rod makes contact (the push-rod is hollow with a hole on both ends, so the oil that escapes the lifter is forced up through the rod and lubricates the rocker cup. The spring in the lifter keeps the push-rod tight but is not strong enough to rock the cylinder head valve - this is where the oil holds the plunger with enough resistance to rock the valve against the valve spring.

So to answer your question, yes, the lifters can be forced down a bit and once they bottom out they will rock the cylinder head valves. So you don't have to worry that you are going to damage anything by tightening up the rocker shaft - there is enough clearance. You will see that some valves start rocking as you tighten the rocker shaft down.

It's a good idea to fill the lifters with some oil before fitting and it's normal for a bit of lifter clatter on first start-up - this should go away in a few seconds as the lifters fill to capacity, so don't be alarmed.