The lat­est de­vel­op­ment – belt-in-oil

Car Mechanics (UK) - - Instant Expert -

Ten years ago, in re­sponse to car man­u­fac­tur­ers’ de­mands to re­duce weight and ex­haust emis­sions wher­ever pos­si­ble, Dayco in­tro­duced the belt-in­oil (BIO) tim­ing belt. Pre­sented first on the Ford Lynx 1.8-litre TDCI, the BIO tim­ing belt re­placed ear­lier en­gines’ Du­plex chains, ten­sion­ers and sprock­ets with a spe­cial oil-re­sis­tant belt that comes pre-as­sem­bled with its own ten­sioner and pul­leys. Un­for­tu­nately, cus­tomer ex­pe­ri­ence with this spe­cific ap­pli­ca­tion has not been as pos­i­tive, com­pared to the ear­lier main­te­nance­free chain. As with dry tim­ing belts, the teeth are prone to strip­ping but, as the BIO belt is sit­u­ated within the en­gine, the frag­ments can work their way into the oil pump, or else block the oil pump strainer within the sump. Any low oil pres­sure warn­ings, or difficulty in build­ing pres­sure im­me­di­ately fol­low­ing a cold start, might in­di­cate a BIO prob­lem.

Our tech­ni­cal part­ner for this ar­ti­cle, TLC Ford of Wolver­hamp­ton, re­ports that many cus­tomers in­sist on mak­ing a belt-to-chain con­ver­sion to pro­vide a life-long so­lu­tion. Best of all, this task is sim­ply a bolt-on con­ver­sion that is de­tailed later in this fea­ture.

Given their draw­backs, one might pre­sume that BIO belts are classed as an ex­pen­sive mis­take never to be re­peated, but you would be wrong. The Ford Eco­boost 1.0 Fox en­gine, for ex­am­ple, has a tim­ing belt run­ning in 0W20 oil, while both Peu­geot-cit­roën and the Volk­swa­gen Group have adopted BIO sys­tems also in their small-ca­pac­ity

en­gines. How­ever, these units are very new and only time will tell whether BIO tim­ing belts are as de­pend­able as many car-mak­ers claim, es­pe­cially given long ser­vice in­ter­vals and the pro­lif­er­a­tion of stop-start sys­tems, both of which place ex­tra strain on the belt. Speak­ing to the mo­tor trade press, Her­man Schulte, head of tim­ing belt de­vel­op­ment at Con­titech, said that BIO tech­nol­ogy was nec­es­sary to help car-mak­ers meet their 2020 CO2 tar­gets of 95g/km, as well as mak­ing the tim­ing gear lighter and more com­pact. Com­par­ing both the orig­i­nal Du­plex chain de­sign with the BIO belt for Ford’s 1.8-litre TDCI (see Step 26), the lat­ter is con­sid­er­ably lighter and likely to be sig­nif­i­cantly cheaper to pro­duce.

If work­ing on cars with vari­able valve tim­ing, be wary of any ex­tra work re­quired, such as ad­di­tional in­struc­tions to un­load the hubs. Con­sider also re­plac­ing any worn hubs, while the tim­ing belt is be­ing re­newed.

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