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Toyota 1.8vvti engine problems

 The oil consumption issues afecting 1zz 1.8, 3zz 1.6 & 4zz 1.4 engines is caused by

a combination o seveal issues, leading Toyota to ma!e seveal changes to the

engines up to aound mid "##$ %hee they managed to cue the issues,

1. nsu'cient oil capacity, pe "##$ engines only came %ith 3.( lites o oil, this

caused the oil to emain vey hot all the time educing the cooling afect the oil has

on the bac! o the pistons. The continued high oil temps causes the oil to degade

and sludge e)cessively bet%een sevice oil changes.

 Toyota inceased the oil capacity om 3.( to 4." lites educing the oil temps in the

engine. * +T -n post "##$ cas Toyota inceased oil capacity to 4." lites, -n pe

"##$ cas %hich had the o'cial modications caied out due to e)cessive oil

consumption the oil capacity %as aised to 4.(lites e)cept o /0"s %hich stayed

at 3.(lites due to the compact 2 shallo% sump tted to them

". oo piston design, the ea o the piston only had 4 oil %ays allo%ing the hot oil

coming om the piston ing oil scapes to pass a%ay om the piston ings. This

meant that the oil stayed at the hottest pat o the piston co%n o too long

e)acebating issue 5 1 %hich in tun allo%ed the oil %ays to sludge up. -nce

sludging stated the oil %ould eventually stat to bun and haden aound the ings

this stated to %ea a%ay at the boes eventually misshaping them. ue to the

i!osil coating applied to the boes they should not be eboed o honed meaning

 Toyota eplaced any bloc! sho%ing even the slightest o damage.

 Toyota edesigned the pistons to include 8 oil %ays %hich allo%ed the oil to pass

a%ay 7uic!e.

3. The use o poo 7uality o ovely thic! oils *thic!e than $%3# inceased the li!ely

hood o the issues above occuing. Toyota noted that even deales %hee using oils

such as 1#%4# and 7uic!ly pointed out that although the o%nes manual listed

1#%4# it %as o %ame climates and that $%3# %as the peeed gade and

insisted that deales use $%3# %hen sevicing and epaiing 5zz engines.

4. oo piston ing design, n an attempt to educe iction, incease e'ciency and

lo%e emissions the engine designes poled the piston ings to a shap point

educing the contact point on the boe, this on its o%n only inceased oil

consumption slightly but %hen combined %ith issues 1," & 3 caused the piston ingsnot scape the ovely thic! oils efectively.

e% piston ings %hee designed %ith a lage contact aea and highe ing tension.

nitially Toyota tted ne% bloc!s along %ith modied pistons, ings, themostat * to

lo%e engine unning temp and a modied dipstic! * to sho% the ne% 4.(lite

levels they also ecoveed the old bloc!s eventually leading to them s%itching the

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appoved epai method to emanuactued shot bloc!s ully assembled %ith the

modied pats.