stan's 240D
stan's 240D
1. cap off, cold engine. run until warm, leave cap off. fondle the upper hose until you feel it get HOT (t-stat opens), should take a few minutes to "seems like forever" depending on ambient temp, the upper hose SHOULD get quite warm slowly, but you should feel an OBVIOUS "switch" where the hose goes from "borderline uncomfortable" to "OMG!! THAT"S HOT!!" to the touch, observe flow.
you should see NO appreciable flow while the t-stat is closed, and when you feel it open, you should see the radiator RAPIDLY lose coolant, and hot coolant surge in rapidly to replace it. gulp and surge is fine. VERY active vortex is awesome. lazy pokey, or non-evident circulation is "results not so good".
rapid gulp, pokey lazy refill (cross flow rad), or hot water overflowing the cap (vert flow rad)? clogged core in the rad. overflow, however, can also SLOWLY happen in either vert or cross flow rads if the water pump isn't sucking at the cold tit. that will be evident by the thermostat NOT cycling (hose stay way hot), where with a clogged vert core, it will be a rapid displacement, and the t-stat will close (the gulp of cool water from the bottom tank cools the mass as it mixes, doesn't happen with restricted inlet).
IF you see flow before the t-stat is felt to open, you have a stuck open t-stat. if the flow is slow, or you just feel a "slow temp creep" in your upper hose t-stat observation (where it creeps up to "switch" temp with a mild, or unperceived "temp change" to touch, but you see the evidence of greatly increased flow), you have a "stuck cracked", or drilled t-stat. t-stat drilling is BAD, especially in hot weather. it reduces "residence time" in the rad. it increases cold tank temps. if the t-stat flange was supposed to be "swissed", M-B probably would have had the foresight to do so.
if you find no apparent reason for flow problems (stuck closed t-stat, kinked hoses, etc), the list of culprits is pretty narrow. monster crud in passages (always a possibility with auto's old enough to purchase beer), bad pump (ever seen an impeller eroded smoothy-shiny by an environment of iron oxide slurry? they don't do much, yet rarely leak due to lack of load, lol), or, in an idling, unpressurized test as above (which will NOT collapse the cold hose with suction, unless it's vacationing in sponge city) a hose or hoses have internally de-laminated (it forms nice little parachute choke valves, and is completely undetectable without tugging the hose off, and often defies visual inspection on removal... the only GOOD test if it suspected is running something like a tape measure down the hose, "feeling" for the tongues).
2. assuming you got flow, t-stat cycling, and you're sure your fan is moving in sync with the pulley (mark both use a strobe to check relationship), next we pop on the cap (still running, hot), and see how long it takes for the upper hose to get hard (pressurize the system). should take about 3-5 minutes (less is ok if you're in hades-like conditions, but no less than 2 minutes). too quick? head gasket or cracked CC, liner, etc. no pressure? bad cap. pressures up in 2 1/2 minutes on a hot afternoon? fandamtastic!! 2 1/2 minutes in wisconsin in january? probably not so good. 30 seconds anywhere this side of venus? WAY bad news. ok, pressured up nice? now for the eye hand coordination test: eyeball on lower rad hose, hand on upper rad hose, other hand on throttle linkage. when you feel the t-stat open, rapidly blip the throttle open and closed. watch the hose (lower rad). does it wiggle and jiggle? that's ok, so long as it isnt kinking doing so. does it undulate AT ALL (look like it's narrowing and expanding along it's length, or "snaking")? any undulation, it's probably collapsing internally from suction.
that's about it for cooling systems. if everything checks out, i'd say sludgy passages (that previously mentioned iron oxide slurry makes an awesome crust). such crust is a terrible heat transfer medium. "old school" marine low speed engines used to get flushed with kerosine as coolant (for moderately nasty blocks) or turpentine (for incredibly bad blocks). acids can be problematic, some react with the oxide and form a very heat inefficient "protective coating" that rivals parkerizing in it's ability to resist removal by just about any means short of abrasives. if others vouch for the citric acid, it's worthy of trying it out. just be prepared to have to replace the water pump afterwards, sludge crud often piers up seals past their prime
edit: almost forgot: look through the air passages (the fins) of your rad. cruddy? suitable cleaner for crud type, sprayed on generously form both sides. rinse with hose from the INSIDE (blast it out the same way it went in, rather than jamming it deeper). if the rad/chassis combo had a factory shroud, USE THE SHROUD. it greatly reduces fan pumping losses (without the shroud, tangential flow like your turbo comp wheel outlet, with, more linear). more efficient pumping equals more air flow equals better heat exchange for any give residence time in the tank
marshall13
05-17-2014, 04:46 PM #233not to be one of the above mentioned "know it alls", but did your lower hose have a spring in it? lot's of other 4 wheeled beasties collapse the hose with suction, cutting flow if they don't have a spring, even with "hoses that don't need it". of course, water pumps and radiators (as well as fan clutches) that are old enough to buy beer are good suspects as well.
1. cap off, cold engine. run until warm, leave cap off. fondle the upper hose until you feel it get HOT (t-stat opens), should take a few minutes to "seems like forever" depending on ambient temp, the upper hose SHOULD get quite warm slowly, but you should feel an OBVIOUS "switch" where the hose goes from "borderline uncomfortable" to "OMG!! THAT"S HOT!!" to the touch, observe flow.
you should see NO appreciable flow while the t-stat is closed, and when you feel it open, you should see the radiator RAPIDLY lose coolant, and hot coolant surge in rapidly to replace it. gulp and surge is fine. VERY active vortex is awesome. lazy pokey, or non-evident circulation is "results not so good".
rapid gulp, pokey lazy refill (cross flow rad), or hot water overflowing the cap (vert flow rad)? clogged core in the rad. overflow, however, can also SLOWLY happen in either vert or cross flow rads if the water pump isn't sucking at the cold tit. that will be evident by the thermostat NOT cycling (hose stay way hot), where with a clogged vert core, it will be a rapid displacement, and the t-stat will close (the gulp of cool water from the bottom tank cools the mass as it mixes, doesn't happen with restricted inlet).
IF you see flow before the t-stat is felt to open, you have a stuck open t-stat. if the flow is slow, or you just feel a "slow temp creep" in your upper hose t-stat observation (where it creeps up to "switch" temp with a mild, or unperceived "temp change" to touch, but you see the evidence of greatly increased flow), you have a "stuck cracked", or drilled t-stat. t-stat drilling is BAD, especially in hot weather. it reduces "residence time" in the rad. it increases cold tank temps. if the t-stat flange was supposed to be "swissed", M-B probably would have had the foresight to do so.
if you find no apparent reason for flow problems (stuck closed t-stat, kinked hoses, etc), the list of culprits is pretty narrow. monster crud in passages (always a possibility with auto's old enough to purchase beer), bad pump (ever seen an impeller eroded smoothy-shiny by an environment of iron oxide slurry? they don't do much, yet rarely leak due to lack of load, lol), or, in an idling, unpressurized test as above (which will NOT collapse the cold hose with suction, unless it's vacationing in sponge city) a hose or hoses have internally de-laminated (it forms nice little parachute choke valves, and is completely undetectable without tugging the hose off, and often defies visual inspection on removal... the only GOOD test if it suspected is running something like a tape measure down the hose, "feeling" for the tongues).
2. assuming you got flow, t-stat cycling, and you're sure your fan is moving in sync with the pulley (mark both use a strobe to check relationship), next we pop on the cap (still running, hot), and see how long it takes for the upper hose to get hard (pressurize the system). should take about 3-5 minutes (less is ok if you're in hades-like conditions, but no less than 2 minutes). too quick? head gasket or cracked CC, liner, etc. no pressure? bad cap. pressures up in 2 1/2 minutes on a hot afternoon? fandamtastic!! 2 1/2 minutes in wisconsin in january? probably not so good. 30 seconds anywhere this side of venus? WAY bad news. ok, pressured up nice? now for the eye hand coordination test: eyeball on lower rad hose, hand on upper rad hose, other hand on throttle linkage. when you feel the t-stat open, rapidly blip the throttle open and closed. watch the hose (lower rad). does it wiggle and jiggle? that's ok, so long as it isnt kinking doing so. does it undulate AT ALL (look like it's narrowing and expanding along it's length, or "snaking")? any undulation, it's probably collapsing internally from suction.
that's about it for cooling systems. if everything checks out, i'd say sludgy passages (that previously mentioned iron oxide slurry makes an awesome crust). such crust is a terrible heat transfer medium. "old school" marine low speed engines used to get flushed with kerosine as coolant (for moderately nasty blocks) or turpentine (for incredibly bad blocks). acids can be problematic, some react with the oxide and form a very heat inefficient "protective coating" that rivals parkerizing in it's ability to resist removal by just about any means short of abrasives. if others vouch for the citric acid, it's worthy of trying it out. just be prepared to have to replace the water pump afterwards, sludge crud often piers up seals past their prime
edit: almost forgot: look through the air passages (the fins) of your rad. cruddy? suitable cleaner for crud type, sprayed on generously form both sides. rinse with hose from the INSIDE (blast it out the same way it went in, rather than jamming it deeper). if the rad/chassis combo had a factory shroud, USE THE SHROUD. it greatly reduces fan pumping losses (without the shroud, tangential flow like your turbo comp wheel outlet, with, more linear). more efficient pumping equals more air flow equals better heat exchange for any give residence time in the tank
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