Design Of Booster Heater System

[Guest Hankinson]

Dear experts/non-experts-like-me

 

I took the morning off work today here in sunny (?) Holland to start investigating the seemingly well-known "emission of grey smoke" problem. I'm glad I'm not alone. Feel good about that.

 

First I did my homework and read most of the excellent posts here (thank you) related to the booster heater. After reading, I narrowed it down for time being to Cause No.3 from TECHNICAL SERVICE BULLETIN No.118/2000 Car and Light/Medium Commercial 19.10.2000 which someone kindly posted and says QUOTE 3. Thick, "continuous" emission of grey smoke. Cause: Booster heater metering pump is faulty. Excessive deposits in the burner of the additional heater. Burner is over saturated with unburned fuel. Remedy: Install a new booster heater metering pump and, if necessary, a new booster heater. UNQUOTE.

 

So, I went outside to confirm I had continuous rather than intermittent emission of grey smoke.

 

Here's my question. I started the engine and the booster started soon thereafter (since air temp is below 10 deg C and coolant is cold). But then in the next 20 minutes of engine idling and occasional dipping the gas pedal by me it transpires that the emission is not continuous. From the booster exhaust comes grey smoke (excessive, stinking etc) for a few tens of seconds and then eases off and then emits little or no smoke - just gently (very gently) emitting warm/hot fume/air. This then repeats after 1-5 minutes or so.

 

What reasons could there be for me lacking "continuous" operation of the unit i.e. continuous grey smoke (until shut down i.e. until the working temperature is reached). Is anyone into the design of the system?

 

Alan, Rotterdam

ps Especially a big thanks to Ivor and his post of May 1 with all the pictures/info. V interesting and well posted.

[Ivor_E_Tower]

All I can think of is something that was mentioned before - the heater has several settings, and on some of them, yours is over-fuelling.

I do not know how the unit works out when to reduce its output and switch to a lower setting; maybe it works from ambient temperature, water temperature or a mixture of both - anyone else know ?

[Guest Hankinson]

Thanks Ivor.

I got round to dropping the booster heater on its hoses (with a view to eventual self replacement] yesterday. Struck me that I have FAR TOO much soot (see photo) which may have clogged up in the system. It's 1-2 mm thick. This has led me to think that maybe bio diesel (once or maybe twice filled up on our way back from Austria last Feb) has caused the problem. The problem started after this trip.

 

Any thoughts folks? I'm in the dark...

[Masked Marauder]

I am going to speculate something different.

 

Perhaps your water pump is not circulating the coolant efficiently at idle? This would cause the booster heater to overheat the water in it's heat exchanger and go onto reduced power or off all together. Then when you rev the engine you push the hot water out and it re-lights. The puff of smoke you see when it lights is perfectly normal.

 

But the soot could be reducing the airflow, and it won't harm to clean it out the exhaust.

 

Try running the heater with the exhaust and air intake off, you will know it is working then, it is so loud!

[Guest Hankinson]

Thanks Marauder. Appreciate the thinking.

I ran the car without the exhaust and air intake. Still the same result. You may have a good point about the water pump. Although I'd expect this to have a mechanical impeller and would would always provide some flow even at low revs.

 

I fear I'm still faced with advice from BULLETIN No.118/2000 to Install a new booster heater metering pump and, if necessary, a new booster heater.

 

Before I go that far I'm still hoping to keep my options open...

1. I was wondering about servicing/cleaning out the booster myself i.e. dropping it, dismantling it, cleaning out the 2mm layer of soot and putting it all back. Is this a realistic proposition?

 

2. Contacting the OEM in Germany and see if there is a willing Engineer there who'd trouble shoot for me over the phone. I've tracked down the factory from the manuf. label on the unit.