A Quick test to see if you have a leaking head gasket

[wayne petty]

i have actually used this for several years.. i don't recall if i ever posted it here..


   Cold engine. remove radiator cap. place a piece of saran wrap over the radiator filler neck.  push a depression in the saran wrap.. seal it in place with a rubber band. squeeze an upper hose to verify you have a good seal.. the depression should pop up and go back down when you release.   you may or may not  need to block the overflow hose depending on the level of coolant in the overflow reservoir..  start the engine for 15 seconds.  the depression in the saran wrap should NOT have inflated within the first 15 seconds of a cold start unless there is a compression or combustion leak into the cooling system..


this won't find every blown head gasket.. it won't find cracked heads other than in the combustion chamber into the coolant.. but it is a heck of a time saver..



the next step if it does inflate.  a cylinder leak down test.. with the saran wrap still on the radiator filler neck..

if you inflate the depression when you apply compressed air with the piston at TDC on the compression stroke.. you have proven a leak.. this saves you hours of tear down .. just leave it hooked to that cylinder.. call the customer.. when they show up.. hook up the shop air hose again.. bubbles appear and the job is either sold of the car is heading to the junk yard..


when you run across a car or truck with a blown head gasket... drain the radiator..  put a paper on the steering wheel indicating this car has a blown head gasket and no coolant in the engine.. do not operate..

after you have drained the radiator.. start the engine.. let it run for a minute to dry out the cylinders..  you have a choice of spraying in some WD40 just as the engine is being shut off to lube the cylinder walls ..

this no coolant in the engine may prevent coolant/water/rust damage to the cylinder walls taking a head gasket job with surfacing the heads to a complete rebuild ..

leaving a car assembled but without coolant.. also gives experienced techs the ability to move the car around under its own power... how far across the parking lot and into or out of your service bay can do make it in a minute..  you are NOT going to do any damage to a COLD engine by running it for a minute.. other than saving your and your friendly techs who would be helping you push the dead cars around back..

this is probably in the wrong forum.. but i am sure that it will get moved where it should be..

happy thanksgiving.

[jaybee]

Good tip Wayne, thanks!

[chimp koose]

good tip ! great time saver.