Submitted by: Tom I Stables

Vintage auto buffs restoring vintage Chevrolets may require basic service and diagnosis of standard run of the mill 400 and 400/475 Turbo Hydra-Matic automatic transmissions of their Chevys that are their automotive restoration project. They may want to do the work themselves or their local GM dealership service department or vintage auto community trusted mechanic may just be too busy. It may be the case that their local auto restoration expert of perhaps the local Chevy guy is instead perhaps working on more exotic cars and components and thus has given them the short shift. Here is a quick service guide for quick service on 400 & 400/475 GM especially Chevrolet Turbo Hydra-matic automatic transmissions especially in dealing with diagnosis of the causes of basic and simple transmission fluid leaks.

The Chevy enthusiast may be quite hamstrung and even alarmed to find fluid leaking out of the bottom of their project car onto the pavement or garage floor. Have heart and persistence. These older GM products are not only built like Chevies they were solidly built, relatively simple and made easy to work on. This you might notice is unlike mainly of the domestic and imported Japanese, Asian and European newer vehicles that your shop will come across and cannot really work on in any practical sense. That is of course without specialized tools available only and at and through you guessed the auto makers local dealerships service center and their factory trained mechanics and technicians.

The Turbo Hydra-Matic 400 and 400/475 transmissions are labeled as fully automatic units consisting primarily of a three element hydraulic torque converter and a compound planetary gear set. Three multiple-discs clutches. One sprag unit, one roller clutch and two bands provide the friction elements to obtain the desired function of the planetary gear set.

The first task in this series is to check fluid level which should be fairly standard procedure for auto owners. At normal operating (non cold being driven or warmed up) fluid levels on the transmission dip stick should be at the full (on Chevrolets and older GM products) or in some other trucks, cars and now SUVs at the max or maximum marking. Specifically with this turbo hydra-matic setup in case of cold tranny fluid measurements the level should lie approximately inch below the Add mark on the stick. Emphatically put only Dexron fluid should be used and nothing else ever.

Note that possible points for oil and transmission fluid leaks may generally occur at the following points: transmission old pan leaks resulting from attached bolts not correctly torqued damaging the pan gasket itself, pan gasket mounting face not flat. Rear extension leaks resulting from attaching bolts not properly torqued, rear seal assembly damaged, O ring in extension case damaged, porous casting. Other possibilities include case leaks resulting from filler pipe O ring damaged, modulator O ring seal damaged and governor cover O ring seal damaged. Next in line if you still have not diagnosed the case of leaking fluid or fluids onto your garage floor or driveway are speedometer ring O ring damage and breach, manual shift seal damages ,line pressure tap plug leakages resulting from worn threads or lacking sealing compound.

Lastly front end leaks may well originate and result from damaged front seal pumps that attach bolts and seals that have during the course of years and many miles coming loose and / or damaged as well, defective converter welds that while they may of held up previously have also during the course of time and miles given way. In addition you may choose to look for pump O ring seals that are damaged.

However the cause of your Dexron transmission fluid leaking onto your driveway or garage floor may be much simpler and easier to correct. If oil comes out of the vent pipe, then simply put your trouble may all in all be caused by a simple overfilling of fluid in your transmission , water in the fluid or a pump to case gasket simply mis-positioned.

About the Author: Tom I Stables

Eagle Ridge Chevrolet GMC Buick

Vancouver GM Auto Dealer

Trucks for Sale Surrey British Columbia

Pitt Meadows Auto Sales

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