G300 petrol overheating
I've now driven my 'new' G for about 12000 miles since I bought it last November and really like it. There is only one problem. When I'm going uphill or am landed in stop-go traffic for a while, the engine water temp rises to just below the red line mark on the temp gauge. It never actually hits the red, but is always VERY close. It can stay up there for a 10 minutes or so, before it come 'down' a bit. Whilst on the motorway or A-roads, the temp runs between 80 and 90 degrees.
I've noticed that 463s have radiator issues, but thought this only applied to the 'older' ones. Mine is a 1997 plate vehicle. Can this still be the same issue? I have already changed the themostat valve for a new one and the problem persists. Idle is also under control at about 7-800rpm in traffic. The problem, needless to say, is an issue as my G tends to be loaded to the gills pretty much all the time. The cars now got over 120k miles on the clock.
Any suggestions as to what might be going on?
Ph
Read the manual
http://www.foro.pieldetoro.net/web/MERCEDES/detalle.php?MANUAL=21
It should say that the temperatures between 80 - 110 C is okay. If it goes to red, then you should take counter measures, written in the same manual.
hi have you checked the viscous coupling on the fan ? has problem just arisen, or got gradually worse , have you tried flushing the cooling system and adding fresh antifreeze/coolant . david
worth checking the radiator itself as well for mud/dirt as this would adversly affect its ability to shed heat
Hi as soon as you get the temp up to 80/90c stop the engine and feel all over the matrix of the radiator for cold areas any at all and the rad is partially blocked and a recore/new one will be required.is there any water loss-frequent filling?
What year is yours? Mine is 1991 and had 2 radiators in as many as 10 years, due to blockages. Some people say it is because the aluminium fins run horizontally which allows sediment to collect or whatever, but at any rate I would suspect that and the viscous coupling, as advised by our experts, have a feel for cold spots a few minutes after start up.
Also, check under your bonnet to see if the thermostat cap is metal or plastic. The plastic one fails catastrophically at about that temp (110-120) it happened to me and shakir and will probably happen to you if you still have the plastic one + overheating problem! It came with it from the factory, later cars had the metal as standard. The part is only like £20-30 so not worth getting stranded with no coolant over it.
For more info:
http://www.pointedthree.com/disc/forums/showthread.php?tid=14383&posts=1...
You're most welcome. I keep telling myself the beauty of the M103 is its simplicity, there are only so many things you can change :D
btw. There is a coolant recommended by MB for "corroded cooling systems" which is supposed to fend off corrosion in these engines/radiators in particular. KFM Typ 30, part number far as I recall
A000989162514 (not cheap, £35ish? but you only need to change it every 2 years).
http://www.2phast.com/500e/techdocs/coolant_Typ_30b.pdf
MB parts HQ at Milton Keynes only has 3 left as of this week (1 coming my way). But you can always get it from Germany if not here. Just make sure it's the 4L bottle not 1L! 1 of the big bottles should be enough.
Yet more reference reading material, can't have too much background on the issue!
http://www.pointedthree.com/disc/forums/showthread.php?tid=14322&posts=7...
mine is quite the opposite,
i always have to top up the coolant fluid every week (no sign of leakage that i can see), but the temp very rarely reaches 90c. most of the times it stays around 80-85c during heavy traffic jam in 35c weather, or around 75-80c on a nice highway cruise.
it's been like this for almost a couple of years now since i changed the radiator, coolant tank cap, water pump & thermostat. viscous fan is ok, but i suspect getting a bit weak because A/C loses its cool if the vehicle sits in a traffic jam for a while. but as soon as it gets moving again (in considerable speed) the cool air returns.
sorry for jacking the thread
unusual, specially in your climate! get a good flashlight, and take a peek under the engine, from below the car, on the exhaust manifold side, where the head meets the block (the head should be shiny aluminium protruding slightly). If you see signs of water seepage, that might be where it's going, most often as vapour so you won't see it but the trails will be obvious.
i always have to top up the coolant fluid every week (no sign of leakage that i can see),
If you can not see where you are leaking your coolant, then it is very likely to be the water pump leaking. To a point this leak is self healing, in so far it only leaks as the engine warms up and cools down for a short spell, out side of this boundry the leaks self seal. This is why you can not spot it.
Carefully look under the water pump or the crankshft puley just purhaps you may be able to see water stains of leaks from the pump.
Cheers,
When I'm going uphill or am landed in stop-go traffic for a while, the engine water temp rises to just below the red line mark on the temp gauge. It never actually hits the red, but is always VERY close. It can stay up there for a 10 minutes or so, before it come 'down' a bit. Whilst on the motorway or A-roads, the temp runs between 80 and 90 degrees.Ph
Most probably the viscous fan, when the engine is hot, rev the engine, the viscous fan should cut in with a loud growling noise, if you do not hear difference in tone, it is the viscous fan you need to replace. This is not cheap.
Cheers,
This model suffered from rad problems, the cores run horizontal so gradually furr up, my guess is recon rad needed.if your losing water my guess is when it's getting to hot it's blowing put the expansion overflow pipe, so you won't see any water when you come to a stop, unless you get out and have a look while in traffic and check the pipe to see if it's blowing out overflow. As a precaution bend over one of the leafs to lock fan on to run permenatly and go sit in sine traffic and see if it gets hot.
Have found the cause. Viscous unit is totally dead: can stop it when temp is over 110 degrees with my hands and no pain! This is typical as the car is now abroad until the Autumn. Anyway, Peter Perfect I just want to thank you for the G-botch of the summer (i.e. twisting one of the fins into the viscous unit thereby locking it.....I also added cable ties around the fins and through the holes of the round cup that is held between the pulley and the viscous unit for good measure). I have a howling, but cool, G in traffic and up hills with 33 degrees ambient temperature. The new unit is on order.........
Also thanks to the others for your input.
ph
Glad you got it sorted in the end.
Hi Again,
One final question:
I now have the replacement coupling unit (part number 103 200 11 22). For some reason it is called a magnetic coupling. Is this an error in the translation as it looks like a normal thermo coupling (also there are no wires anywhere to make a magnet work).
As the car is in the Med I'm going to have to take tools with me to fit it. Does anyone have an idea what size the nut is that hold on the unit? Is it a 32mm or 36mm. If it is none of these, then do I need a special fan spanner from MB to change the unit?
Any advice is always appreciated.
Thanks in advance/ph
Yes, it is obviously a translation error: it has a viscous coupling.
Don't know about the nut in your engine, but in mine (OM603) the coupling is held by a 8mm hex nut. See tutorial I made for a Spanish forum on how to replace water pump (too busy to translate!):
Cambio de bomba de agua y lÃÂquido refrigerante de motor.
Este brico es válido para motores OM601 (W201 190D) OM602 (W201 190D 2.5, W124 250D, W460 250GD, W461 290GD y W463 250GD) y OM603 (W124 300D y W463 G300D). También puede valer para otros diesel montados en turismos y furgonetas Mercedes. El brico lo he hecho sobre mi G300D de 1991.
Después de poco más de tres años y 35.000 kilómetros en el motor nuevo se me ha ido la bomba de agua. Me dicen que es hasta cierto punto normal en motores que se han pasado en los almacenes de la Mercedes unos cuantos años, que las juntas se resecan y que luego fallan. El caso es que desde hace algunos kilómetros notaba que me perdÃÂa lÃÂquido anticongelante cuando lo dejaba parado y comoquiera que la bomba no se puede reparar, hay que comprarla entera.
Antes Mercedes tenÃÂa la buena costumbre de ofrecer piezas como la bomba de agua de intercambio, con lo que después de devolver la vieja, la reacondicionada saÃÂa por unos 45 euros. En el caso del motor OM603, que es el que monta mi G300 Diesel, esto ya no es asày hay que comprarla bomba nueva por unos € 120 + IVA.
Intenté buscar la bomba en el Valeo local y en otra tienda de repuestos del pueblo y me pedÃÂan entre € 80 y € 100, asàque me decidàa buscarla en Ebay Alemania. La verdad es que habÃÂa un montón de proveedores y una tremenda variedad de precios, pero al final me decidàpor comprarla en la cooperativa del Taxi de BerlÃÂn, que son muy serios y venden piezas de calidad:
http://myworld.ebay.co.uk/te-taxiteile
La bomba la fabrica PEX en Alemania y me costó, con portes incluidos, € 51.45
El precio según catálogo en la página de PEX es de € 86 más IVA (al 19%) y más gastos de envÃÂo, luego el precio era excelente. http://www.pex.de
Sólo hacer la salvedad que algunas fotos las he tomado en el montaje posterior y no en el desmontaje inicial.
Bueno, pues nos ponemos manos a la obra. Lo primero que hay que hacer es retirar la carcasa de plástico que rodea al ventilador. Para ello quitamos primero el pasador que sujeta el manguito que conecta el vaso de expansión con el radiador. Después, hay que girar la pieza de plástico interior hacia la derecha (hacia donde pone "Open") para soltarla:
A continuación hay que quitar las dos grapas que sujetan la parte anterior de la carcasa de plástico al radiador. Una vez retiradas, podemos sacar esta carcasa tirando de ella hacia arriba:
A continuación procedemos a destensar la correa de accesorios del motor. En los motores OM601, OM602 y OM603 esto es muy sencillo. Primero quitamos la tuerca que estaba en el agujero que se vé sobre la pieza negra de la siguiente foto y metemos un destornillador como se indica en la foto y hacemos palanca girando en sentido contrario de las agujas del reloj, con lo que quitamos presión sobre el tornillo del tensor y podemos empujarlo hacia atrás, liberando asàel tensor.
A continuación procederemos a retirar el conjunto viscoso-ventilador. Para ello necesitamos una llave allen de 8 mm y una buena barra donde ajuste la llave para hacer palanca, pues el tornillo del viscoso va apretado a 45 Nm y está durillo. Además, necesitamos una buena barra de las de hacer palanca (wrecking bar) para sujetar el viscoso por el estriado de detrás y poder aflojar el tornillito, porque si no será imposible:
Una vez retirado el viscoso, procedemos a aflojar los cuatro tornillos de la polea de la bomba, utilizando la barra y el estriado para que no se nos mueva (obsérvese la barra de la que hablo):
Ahora toca evacuar todo el lÃÂquido del sistema de refrigeración del motor. Para ello deberemos retirar primero la chapa que protege el radiador por abajo y que vá sujeta con cuatro tornillos. Una vez hecho esto descubrimos el caño de evacuación en el lado izquierdo del radiador según miramos el coche de frente. Encima de dicho caño hay un grifo de color rojo. Para no montar un buen lÃÂo, lo mejor es conectar un macarrón plástico al caño y conectar el macarrón a un depósito para evacuar ordenadamente todo el lÃÂquido antes de abrir el grifo:
En el lado derecho (en orden de marcha) del bloque motor hay otro tornillo para evacuar los restos de refrigerante que hayan podido quedar en el bloque. Aquàtambién es posible conectar un macarrón, aunque en mi caso salieron apenas unas gotas, ya que el caño del radiador queda bastante más abajo que este tornillo:
Una vez evacuado todo el refrigerante, procederemos a retirar la bomba vieja, que está sujeta con siete tornillos. Todos son accesibles aunque alguno esté más escondido que los demás. Una vez suelta, tenemos que soltar el la sonda de medida de aceita del cárter en su parte superior, para dar suficiente espacio para retirar la bomba vieja e insertar la nueva. La bomba nueva viene con su junta, como se aprecia en la foto:
La bomba de agua lleva conectada a su agujero de evacuación inferior, un tubo de tecalán de unos 9 cms. El problema es que el tecalán solo se puede manipular con una pistola de calor de la que yo carezco asàque corté un trozo de longitud similar del macarrón transparente que utilicé para evacuar el anticongelante y se lo adosé. Otro truquillo es pegar muy ligeramente la junta a la bomba con pegamento de cianocrilato , para evitar que se mueva al montar la bomba y que tenga pérdidas posteriormente.
Ajustando los tornillos de la bomba. Yo he optado por apretarlos sucesivamente en cruz, para asegurar un buen asiento, y hacerlo con una carraca pequeñita, porque hay que apretarlos a 10 Nm y no tengo dinamométrica tan pequeña.
El proceso de montaje de todas las piezas es como he descrito para el desmontaje pero a la inversa. Utilicé una llave de carraca pequeña para todos los tornillos, salvo el del viscoso, porque los pares de apriete son pequeños y corres peligro de cargarte alguna rosca.
Los pares de apriete son:
Tornillos hexagonales de la polea: 25 Nm
Tornillo hexagonal del viscoso/ventilador: 45 Nm
Tornillos hexagonales de la bomba: 10 Nm
Recordaros que el lÃÂquido refrigerante/anticongelante debe ser cambiado cada tres años como máximo, si no queremos dañar las aleaciones del radiador, bloque y culata.
Suerte!
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Thanks for all the advice. I'll check the rad as I did flush the coolant about 2 months ago (no coolant loss either by the way). Will come back with findings.ph