Best Way To Flush Rad

[marinabrid]

hi all again, still having a problem with the tdi 90 97 year running hot. it all started after a 200 mile trip in which the turbo oil supply pipe started leaking oil. the engine didnt overheat on way back the gauge stayed in the middle as always. it lost around 2l of oil. we changed pipe but then on way home for some odd reason the temp gauge went much higher than normal when i was in a que.

it now runs at the top end of the norm and sometimes goes nearly in the red the fans work and cool it slightly.

we have left it runningfast idle for 2 hours and it doesnt steam over or leak.

it just runnis much hotter than normal. ive changed the thermostat and bled it but i never thought to back flush the rad the original one from 97 . its now the same just runing at the high end. ive had a few expert opinions from its just running higher than normal for some unknown reason to the .... ooooh could be gasket. in the 4 weeks its been like this it hasnt used any oil or water and nothing is mixing and the car runs fine apart form high temp. front and rear heaters work fine so i think the water pump is ok.

one expert rreclons that once these rads overheat one time they are then prone to do it there after. i was going to flush it out so can someone tell me the best way to do this. should engine be cold....do i then refill and run with cap off to vent it. or is there a way to do it differently.

i know from a few years of running these that they are more prone to run cool than hot so something is amiss somewhere just trting to pinpoint whats the cause. it doesnt matter if the heaters on or off it just gets to the smae high temp after around 30 mins of running. thanks

[seatkid]

Get an original thermostat from dealer - I always have had problems with engines running too hot with non original thermostats. The best way to flush the radiator is to take it off completely and using a garden hose and much waving about etc of the radiator core in your back garden......or treat yourself to a new radiator at about Edited June 12, 2007 by seatkid

[marinabrid]

i think that too. the oil light flashed just once 1/2 mile from home and because the temp gauge hadnt gone up more than half way i drove it home without stopping.

whats your opinion on this seatkid ? its very odd i did use an original ford thermostat but it gives the same reading as before very high

[seatkid]

I think you bust the engine.

 

When the oil light flashed, you had no oil pressure......result = metal to metal contact somewhere (e.g. piston/bore)....causing wear and/or extreme localised thermal stress (and warping). Only a matter of time before complete failure of the part affected.

 

The old Tdi engine runs very cool, and when idling hardly needs a radiator at all.

[marinabrid]

OHHHHHHHH the light flased for a millisecond as i went round a roundabout. any suggestions welcome ! what could happen next then ? what bout if i remiove the thermostat and see if that makes a diffrence Edited June 12, 2007 by martinblackett

[seatkid]

Good idea - if it still overheats - check the radiator matrix near the bottom hose - its thats cool then radiator may be blocked.

[marinabrid]

ok i felt the bottom hose this morning after 10 mile trip to work it was luke warm compared to the top hose which was red hot have lost my tis disc as well is rad change on this mode easy affair with air con rad fixed in same place how long should i allow to do job thanks Edited June 12, 2007 by martinblackett

[seatkid]

Hey, check the connection/wiring to the temperature sensor is ok - you may have disturbed something when you changed that pipe, giving a false instrument reading. Other thing is to remove the battery lead for a couple of minutes (check radio code first!) and when you reconnect, the instruments etc will recalibrate on inital start. It might save the effort of a wasted afternoon..... :rolleyes:

[marinabrid]

thanks wil try how hot should the bottom hose be in relation to the top hose at normal operating temp then ? should it feel hot or more sort of warm/cool,

[seatkid]

Normally the bottom hose will be at best warm/cool, only a small percentage of radiator capacity is required to cool the engine unless it is on full load.

 

However, if you run without the thermostat installed, most of the coolant will flow through the radiator and the radiator will be uniformly warm - though this temperature will be much lower than the correct operating temperature.

[marinabrid]

heres an odd one i just been on a run on motoway it ran only slightly higher than normal at 8o mph then when i come off mway the 2 miles home the needle creeps back up to near the red could it be rad block ?

[seatkid]

Certainly a possibility......pull top and bottom hoses, you might want to catch that coolant.

fill radiator through top while blocking the bottom exit, then release the bottom exit and see how fast it comes out, it should come out in a gush.

 

Use only G12plus antifreeze BTW......

[marinabrid]

ok thanks sk will have a go on sunday thanks for all help for now.

[marinabrid]

well ive flushed out the rad and back flushed it, no sign of any sediment , water runs through and out quite fast. i refiled and same thing. temp creeps up to red . i wonder if i have the water pump impeller come off as someone suggested happens on these engines.

is there any way of test for this ? the front and rear heaters seems to runt hot does this suggest that water is getting pumped around ?

what i did notice odd though. while it was ticking over where the top hose goes into the cylinder head where the temp sensor is the hose coming from the head is hot until it gets more or less half way along to where the fan switch is between the hoses in a housing the hose from the housing to the top of the rad is very much cooler as though it wasnt getting pushed around the pipes. and the radiator was cold also top to bottom any further ideas on how to test water pump working ok ? thanks

[seatkid]

Remove the thermostat and run without it. If the engine stays cold, i.e. well below normal then the pump is OK.

[cartman]

Hi Martin,

It sounds like you've got the same problem as me......Read my thread (Running hot over 70) It might save you some expense.......Though no cure at present.

 

Meantime if you find the solution please post back.

[marinabrid]

i know this may be clutching at straws but would a different grade oil maybe help the cooling a bit ? at present i use the 10w40 semi sythetic wondered if a 5w 40 full synth or the other way a 15w40 semi would help ?

[seatkid]

I think you're clutching at straws....... :ph34r:

[marinabrid]

car seems to be running cooler since i flushed it again apart from the usual car shop type flush additives does anyone know of anything better some sort of super chemical to blast the crap away inside. im sure this is my problem

[seatkid]

I think you should read Jackspud's post

[marinabrid]

have read that ! i will take off coolant cap in morning when cold and hopefully not hear hissing is that correct ? how does the cracked head make the expansion bottle pressurize and hiss out when cold Edited June 19, 2007 by martinblackett

[marinabrid]

am gonna try flushing again, heard somewhere that you can add redex or injector cleaner to the water system for a better flush anyone else heard of this i dont want to cause any internal problems !

[seatkid]

If water goes through as fast as you can fill with a garden hose then IMO you dont have a problem with the radiator. If it is blocked then all I would do is try to flush though using mains water pressure, maybe some fairy liquid. Cant see redex doing any good. Try shopping around, e.g. These people or these people to name but two that can supply at around