As I've siad on another thread, I'm thinking about looking at a 2001 Merc E320CDi estate with a view to purchasing. HJ's advice, in capital letters, is to CHECK THE GLOWPLUGS.
My question is, how does one check a glowplug, and what is one looking for? I'll look for evidence of them having been changed in the car's invoice history, but on a physical level how on Earth would one go about doing this on a used car forecourt?
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If it starts cleanly from cold,they're OK.
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Sadly it's not that simple. The problem HJ worries about is the glowplugs often break when removal is attempted... some say the head has to come off to sort this but I think MB specialists manage to resolve at a lesser cost.
Even if the car is fine today in 6mths time one could fail and then you are into the will it/won't it come out gamble.
If you believe this issue exists it needs very serious consideration as it could make a dmf seem good value (yes I know you won't need one but just saying).
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>> the glowplugs often break when removal is attempted
The smaller, 220 and 270 diesel engines are shared with the Sprinter van. At 120,000 - 150,000 miles when you go to change the glowplugs, you find that electrolytic corrosion between the plug threads and the cylinder head has seized the plugs in solid. The usual remedy is to take the head off and drill them out from the inside... New head sometimes needed as a last resort, that's where the forecasted big costs come from. A Mercedes specialist will be clued up on ways around the problem.
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To check the glowplugs, make sure the glowplug lamp on the dash behaves properly.
As these engines are direct injection, they don't need glow plugs working to be able to start unless you're looking at operating in extremely cold conditions.
The best way to reduce the risk of glow plugs snapping is to;
a) remove them while the engine is hot - the aluminium head expands more than the steel glow plug
b) check the Beru website and don't apply any more than the quoted breakage torque to the plug. If the plug doesn't move at this torque, find a specialist with a vibrating glow plug removal impact wrench.
The really important factor to guard against glow plugs siezing in the head is to make sure the taper seal between the glow plug and head is in perfect condition. Carbon leaking past this taper seal is THE biggest cause of glow plugs snapping in the head.
Don't use grease when re-assembling the glow plugs as the extra compression force can damage the glow plug - it squeezes closed a gap which provides a thermal short-circuit. The glow plug will continue to work electrically, but, won't actually be producing the heat it should be doing at the glow plug tip.
I wouldn't bother fitting anything other than Beru glow plugs. The technical pages of the Beru web site are particularly helpful.
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Mercedes Benz E-Class W210 - 01 3.2 Checking glowplugs - jc2
