老雷 寫到:

汽油泵浦在油箱內冷卻的說法,讓我想起網路上的傳言---賓士車換變速箱油一定要先降溫,否則閥體會變形!!!???. 我詢問了中華賓士熟識的專員,得到的回答是---賓士車的變速箱閥體那有那麼不堪,誰看過在原廠保養的變速箱閥體變形?

變速箱要降溫並非閥體變形,主因是熱了油膨脹,你根本無法加足規定的油量(我在996試過,熱車加進去至少比洩出來少了一公升且還不含漏掉的)!MB現在新的7速應該也需要冷到一個溫度才可以換(那種用灌的都是如此),所以不少車主換完ATF後掛點,有些是油量不夠引起,但常出問題的恐怕還是像MB的設計不良!(所以車廠改料的次數就可以得知車輛的優劣)

hibruce 寫到:

變速箱要降溫並非閥體變形,主因是熱了油膨脹,你根本無法加足規定的油量(我在996試過,熱車加進去至少比洩出來少了一公升且還不含漏掉的)!MB現在新的7速應該也需要冷到一個溫度才可以換(那種用灌的都是如此),所以不少車主換完ATF後掛點,有些是油量不夠引起,但常出問題的恐怕還是像MB的設計不良!(所以車廠改料的次數就可以得知車輛的優劣)

坊間汽修廠都以訛傳訛,閥體會變形;事實是您說對了.

722.9(7速,由車底下往上灌),降到60度以下即可換油.

而722.6(5速,有油尺加油孔)換油則不用降溫.

大家討論討論囉(分享相關經驗)~
近代的噴射車因為供油壓力比較高，原廠設計在油箱裡就是為了散熱、與安全(汽油泵泡在汽油裡比較安全，因為不會引起火花)，這兩段話出自高職汽修科教科書，由於我已經畢業二十幾年了，無法找到當時的教科書來給大家看，但是維基百科已經整理很多常識與資訊，可以供大家閱讀參考囉~
As engines moved away from carburetors and towards fuel injection, mechanical fuel pumps were replaced with electric fuel pumps, because fuel injection systems operate more efficiently at higher fuel pressures (40-60psi) than mechanical diaphragm pumps can generate. Electric fuel pumps are generally located in the fuel tank, in order to use the fuel in the tank to cool the pump and to ensure a steady supply of fuel.

http://en.wikipedia.org/wiki/Fuel_pump
以上資訊出自於維基百科連結~~

宜蘭狼 寫到:

As engines moved away from carburetors and towards fuel injection, mechanical fuel pumps were replaced with electric fuel pumps, because fuel injection systems operate more efficiently at higher fuel pressures (40-60psi) than mechanical diaphragm pumps can generate. Electric fuel pumps are generally located in the fuel tank, in order to use the fuel in the tank to cool the pump and to ensure a steady supply of fuel. http://en.wikipedia.org/wiki/Fuel_pump

我指的以前的車也是EFI,有些還是CSI,像我車上怠速壓力就有6.2bar,若是美歸高達7.0bar,而電子噴的普遍在3bar左右!且我看來在油桶裡的pump,實在跟在車外的(同樣是EFI)無異!其實若仔細想,油低過一定程度那就不能散熱,為何沒有車主手冊告知?為何不一半過了就亮燈?若你看過汽車的油桶,甚至我可以做個凹槽把fuel pump放在裏頭,讓汽油亮燈前,pump都可以泡在汽油裡,但我卻沒看過這樣的設計!開車的年數頗長,那些在車外的pump真的壽命比在油桶裡的高得多,且我的壓力更高,絕對不是沒油把fuel pump搞掛!
PS除了安全,噪音才是都改沉桶的原因!

hibruce 寫到:

我指的以前的車也是EFI,有些還是CSI,像我車上怠速壓力就有6.2bar,若是美歸高達7.0bar,而電子噴的普遍在3bar左右!且我看來在油桶裡的pump,實在跟在車外的(同樣是EFI)無異!其實若仔細想,油低過一定程度那就不能散熱,為何沒有車主手冊告知?為何不一半過了就亮燈?若你看過汽車的油桶,甚至我可以做個凹槽把fuel pump放在裏頭,讓汽油亮燈前,pump都可以泡在汽油裡,但我卻沒看過這樣的設計!開車的年數頗長,那些在車外的pump真的壽命比在油桶裡的高得多,且我的壓力更高,絕對不是沒油把fuel pump搞掛! PS除了安全,噪音才是都改沉桶的原因!

再舉個例子,我那台壓力很高的fuel pump(一顆在油箱出來的底盤處,一顆在引擎室內)
1991年至今,依然完好!我幾年前買了2顆怕她掛點,但還沒機會用上!這壓力可是一般EFI兩倍的壓力,他沒泡在汽油裡,在引擎室內更是散熱困難!
有開過MB(我對這較熟)別說外掛的壽命長,換起來也便宜,掛的時候敲一下可能還會作動,不必叫拖車!而沉桶的MB,掛fuel pump真的比外掛得來的頻繁!所以絕非沒油導致真的只是車廠心態改了!

精闢的分享
我也來加碼一篇~
‧ Low fuel level in the fuel tank can shorten fuel pump life. Inform the customer that fuel level affects the life of the fuel pump (gasoline is used for both cooling and lubrication), and fuel with an octane rating specified in the vehicle owner manual should be used.
以上資訊節錄於下方連結~(有興趣的車友可以參考參考囉)
http://www.acdelcotechconnect.com/pdf/imtn_V16I309.pdf

宜蘭狼 寫到:

精闢的分享 我也來加碼一篇~ ‧ Low fuel level in the fuel tank can shorten fuel pump life. Inform the customer that fuel level affects the life of the fuel pump (gasoline is used for both cooling and lubrication), and fuel with an octane rating specified in the vehicle owner manual should be used. 以上資訊節錄於下方連結~(有興趣的車友可以參考參考囉) http://www.acdelcotechconnect.com/pdf/imtn_V16I309.pdf

我因為壞過同一台車兩次在油桶內的fuel pump因為原廠整組爆貴連浮筒也做在一起!所以單換裏頭的pump(一組兩顆)!說實話,除了比較小顆外,跟我用的外掛式的我實在看不出差異!那為何那種掛在底盤下面的fuel pump不需要汽油散熱壽命可以很長,這種泡在油裡的反倒老有人說不要見底才加油這樣有損壽命實在弄得我滿頭霧水!

宜蘭狼 寫到:

精闢的分享 我也來加碼一篇~ ‧ Low fuel level in the fuel tank can shorten fuel pump life. Inform the customer that fuel level affects the life of the fuel pump (gasoline is used for both cooling and lubrication), and fuel with an octane rating specified in the vehicle owner manual should be used. 以上資訊節錄於下方連結~(有興趣的車友可以參考參考囉) http://www.acdelcotechconnect.com/pdf/imtn_V16I309.pdf

看了一下老外的討論,其實fuel pump的熱會藉由裏頭的汽油帶走,那也是為何我說的外掛式不泡在油桶裡,卻有更好的壽命!多數都說吸到空氣(油用盡了)才會導致fuel pump受損!這噴射系統最早fuel pump都在油箱外(90年代後才慢慢改成在油桶內),那時並沒聽過不要低過1/4加油!但改到油桶內就有此一說!!!!
我的車上有顆water cooler(負責冷卻inter cooler),用原廠bosch幾乎變成這車的耗材!後來我看老外,改用johnson船用的,不僅出力一致,體積更小,當然價格更低,用到現在沒再壞過(老外也是說壽命大增)!我想說的過低的油絕非fuel pump故障的主因,製造商給要給多少壽命是計算過的(恐怕保持在1/4是製造商的推託之詞)!多換汽油濾清才是真的!