Most Rav4 vehicles on our roads these days, are mostly the 4cyinder 2.4L engines, with the V6 3.5L engine in the minority.

This Rav4 in particular, was brought to us from another shop for corrections.


CUSTOMER COMPLAINTS
Owner had taken the car there for the following reasons:

1. Loss of power at every upshifts (acceleration).
2. Knocking noise at every cold startups, and whenever the car is driven.
3. Subtle engine misfires.

HISTORY
According to owner, the engine block of the car was broken(it threw a connecting rod), which resulted in replacing the engine block, and transferring the stock pistons, and rings from the old engine.

OBSERVATIONS/DIAGNOSIS
1. Check engine light was lit on the dashboard.

2. Retrieved codes related to evaporative emissions, oxygen sensor, and cylinder 3 misfire pending.

3. Inspected spark plugs on cylinders #1 &3.
#1 was not picked up by the scan tool, but had some form of engine oil fouling.
#3 had no oil fouling on its centre electrode.

4. Opening up the valve cover, the valve train components were really clean.

5. Engine oil used in the engine when the car was at our base was synthetic oil.

A probable reason why the engine valve train was clean so much without carbon deposits in there.

6. All the camshafts and gears were all replaced from the previous shop.

7. Crankshaft journal bearings, thrust washers, piston rings, were all defective.
They showed signs of scouring on them.

8. Pistons themselves had no signs of any damage resulting from thermal or oil starvation causes.
8. Precious shop reused the old top cylinder gaskets, and the piston rings that were in there before.

9. Here was the big shocker to us. During the head job, we also discovered that the valve stem seals, were not properly fixed. We could removed them all by hand.



THE FIX!
Disassembled the engine completely, and replaced all parts that were not replaced in the first place.
1. All piston rings
2. All timing chains and timing chain auto tensioners.

For my engine rebuilds, just like I always say, I use conventional oils just to make the piston rings sit properly, before using the more expensive or synthetic oil, if that's what a vehicle's specifications calls for.

In this job, it is pertinent you have a trained eye, to listen to engine sounds before the rebuilds, and after the rebuilds. That would help to avert future problems, if they are other things to readjust.


The tasks involved in the disassembly, and rebuilding of 2gr engines, are more tasking than a 1gr engine, found in Toyota 4Runners, etc. Just to replaced the timing chains on a 2gr engine, the entire engine has to be removed, while for a 1gr engine, removing the engine is not a necessity.



Thanks for reading.


Regards

Valve cover opened, to inspect the valve train assembly. Notice how clean the valve train is

Engine removed from engine using a hoisting chain.

Observing the timing chains on both the intake/exhaust camshaft gears.

Here's how clean the engine looked like

Here's an example of how a scoured crankshaft shaft journal bearing looks like.
Do not reuse any bearings that has even a slight scratch.

Following

Looking at the engine block bores. The bore diameters on each cylinder were just too much.

We were trying to really get to understand why cylinders #1 was fouled with engine oil, but #3 was not(#3 was only showing a pending code).
If you looked closely on the valves seats areas, you'd notice some difference in colourations. Some were tan in colour, depicting proper combustion processes, while at the other hand, we had some valves, that were not firing at all!(the black wet colouration there).

In this job, especially with the 2gr engines, as compared to the 1grs, organization is the key here.

The valve train components on the 2gr are complex, and can easily be mixed together by mistake, during disassembly.

Take a closer look at how I arranged all the camshaft bearing caps on various banks differently.

I had to get some white cellophane, and write the components on its designated banks(1 or 2).

Pls take note.:
¶ the camshaft rocker arms and pushrods had part numbers inscribed on them.
I never wanted to mixed any of them, nest the engine starts making some noises after assembled.
¶ you could assembly everything, and put them all with the timing chains differently their various valve covers.

Here's how the arrangements looked lime at the end.

Replacing the two small intake/exhaust timing chains would involve the removal of individual camshaft gears, before fixing the chains. Without doing that, it would be difficult for the chains to get through the gear sprockets.

The most delicate part of the job is to ensure that the engine is properly at TDC(timing), before commencing any work around the chains or piston areas.

Without the engine aligned to TDC, engine damage could occur, while rotating the engine.

nice one brother

agba awo respect o

Nice Work

Nice job you are doing.

TRYGO:
In this job, especially with the 2gr engines, as compared to the 1grs, organization is the key here.

The valve train components on the 2gr are complex, and can easily be mixed together by mistake, during disassembly.

Take a closer look at how I arranged all the camshaft bearing caps on various banks differently.

I had to get some white cellophane, and write the components on its designated banks(1 or 2).

Pls take note.:
¶ the camshaft rocker arms and pushrods had part numbers inscribed on them.
I never wanted to mixed any of them, nest the engine starts making some noises after assembled.
¶ you could assembly everything, and put them all with the timing chains differently their various valve covers.

Nice job !

i think the valveshim buckets for the 2gr engine are also self adjusting( i.e they rely on engine oil to take up the cam lobe/ valve shim bucket clearance

it would be another story entrely for the 1/2AZFE engines as those should never be mixed else you may have to do it the hard way (feeler gauges and valveshim bucket chartbook )

@inception. You're perfectly right. That's why I took my time to organized the whole thing. Even the buckets, I had to number them using white marker, according to their positions in either of the top cylinder banks.

I learnt that the hard way when I was under apprenticeship with my boss some years ago.

We had missed the buckets, in a 2AZ engine, while the valve stem seals were replaced.

Immediately we were done, we cranked the engine, only to realised that there was noise as if oil wasn't supplying sufficiently.

We had to get another top from the store to replaced (thank, the replacement top was intact).

They are self adjusting. There was no need to even adjust anything there. Those too care of themselves.

9icetoo what's your experience with the diesel engine Merc?