22R/22RE Timing Chain Tech
The 22R series motor is one of the most durable motors ever designed.  But
like most engines, it does have a weak link.  That weakness is in the timing
chain.  Fortunely, it's curable and if fixed in time can help the 22R provide
many hundreds of thousands of trouble free miles.
Toyota designed some of it's most durable motors in the 1970s.   Those included the T
series engines and the R series engines.   These OHC motors rarely had any major
mechanical problems.
One area that these motors shined was in the timing chain.   Toyota used a dual row, dual
chain system.   When Toyota replaced the 20R engine in 1981 with the 22R series motor, it
continued much of the 20R design, including the dual row chain.  

For reasons unknown, Toyota dropped the dual row timing chain design during the 1983
model year in favor a single row design.   Ever since this fateful decision, Toyota 22R series
motor owners have had to contend with a timing chain system that usually begins to fail at
around 130,000 miles.

Toyota continued the same basic design of the 22R motor, until the 1995 model year, when
the engine was finnally dropped in favor of two new 4 cylinder truck engines for the new
Tacoma, a 2.4 liter and 2.7 liter.   The latter being the version found in the 4 wheel drive
Tacoma.   During it's 12 year rein, the 22R single row timing chain system has had a
consistent problem of failure at higher mileage.   Some owners have gone as long as 200,000
or 300,000 miles with no problems at all, but a greater number have had to replace the
timing chain systems somewhere north of 100,000 miles.

The main components of the Toyota 22R series engine timing chain system are the chain,
the sprockets, the chain guides, and the chain tensioner.  When replacing the timing chain,
all of these components should be replaced at the same time.

The first indication of a problem seems to always rear it's ugly head with the infamous
"start-up rattle."   This is a rattling sound  usually heard for only a few seconds during a
cold start up.   This is caused by a chain, which is stretched out of spec.   The rattling is the
noise a loose chain makes before oil pressure can come up and quiet it down, via lubrication
and the chain tensioner.   Over time, the loose chain, wears down the plastic chain guides.   
These chain guides eventually break, loosening the tension on the chain even further.   At
this point, the start up noise become much louder and lasts much longer.  The rattling noise
may even be constant.   Repairs should be made immediately, because if left unchecked, the
chain will now begin to wear a hole inside the timing cover.  Once worn through, coolant will
be dumped directly into the oil sump.   Although rare, because the engine is usually making
so much noise by this time, if left unrepaired, the chain will
eventually break, causing the pistons to hit the valves and doing great damage to the motor.
 In some cases, the loose chain will skip a tooth, causing the timing go out, or worse,
damaging the valves.   There have been claims that a chain broke or jumped a tooth with no
audiable warning prior.  

Replacing the chain, can be expensive.  Most Toyota dealers charge somewhere around
$1000 for the entire job.   However, any moderately experienced backyard mechanic can do
this job him or herself.  Only basic tools and about 1 full day is required for the first timer.  

This leaves the question of where to get parts.   Buying OEM Toyota parts is always a good
idea.  There are many alternative sources of automotive parts, but too many of them are
substandard to say the least.   However, dealerships charge a great deal of money for OEM
parts.  Is there  another alternative?   How about getting parts that are better than OEM for
about 2/3 the price?  It's not too good to be true.   DOA Racing sells a complete timing
chain kit for approximately $200.

What makes this kit so great is that it uses the exact same parts that Toyota sells at it's
dealerships.   Like most manufactures, Toyota does not make it's own car parts.  It
outsources them to other suppliers.  One of those suppliers is the Japanese Company,
Federal-Mogul.   DOA buys it's timing chain components from Federal-Mogul, so their
chains are exactly the same as the ones you would get from Toyota.   But there is a
difference.   DOA Racing goes a step further and heat treats the sprockets.   DOA's chain
kit just happens to include not only one set of gaskets and oil seals, but two.  Just in case
you make a mistake.   In addition, the crown jewel, DOA does away with the inferior plastic
guides and supplies it's own metal backed rubber coated chain guides.
These new guides will not break like the plastic guides will over time.   Considering that all
of this is 2/3 or less the price of the same parts from Toyota, it's a real bargin.     
Rather than attempt to describe how to replace the timing chain, I've included several
links below to websites that do a good job of that themselves.   I've installed the DOA
timing chain system in my 22RE.   After about 1 year and more than 15,000 miles, I have
not had one problem.  Although with that few miles, one would probably not expect any
problems anyway.
So far, I would highly recommend this product.  
DOA's metal backed, rubber
coated, chain guides.  The
answer to Toyota's  pathetic
plastic chain guides
Not every high mileage 22R owner nessessarily has to go out and replace their timing
chain
system.   But, anyone will more than 100,000 miles on the chain, should be prudent in
inspecting the chain and chain guides on a regular basis.  This involves removing the
valve
cover and inspecting the condition of the chain and checking to be sure that the chain
guides are intact and in place.

Once a worn timing chain and it's components are replaced, the 22R series engine can
go on for many thousands of miles of trouble free driving.  These motors, despite the
timing chain concerns, keep on clocking off 200,000, 300,000 and even 400,000 miles
without any major repairs.
LINKS
More links to come as they become available
DOA RACING ENGINES

6013 Permiere Avenue
Lakewood, CA 90712

(562) 876-6336