Diesel blowby and runaway... A temporary solution

imported_brackie · 16-06-2005, 07:36 AM

Really, the only way to fix this is to rebuild the motor...But, the mod. below worked for me.

History. After the 1.5 diesel Golf had been on the market for a couple of years the runaway problem emerged. The diesel has an extremely high compression ratio of 23.5:1 , so you can imagine the blowby potential! Oil splash and mist were further exacerbating the problem as they could exit the camshaft cover and be drawn directly into the intake manifold without even being drawn through the air filter. VW were very concerned and brought out a modification kit to improve the crankcase breathing so that the fumes being taken into the air intake didn't come solely from the camshaft cover. The kit consisted of a plate to replace the existing connection to the vacuum pump and had 2 hose connections instead of one, a hose that reached to the existing camshaft vent hose, and a "T".
When it happened to me! I'd never had the runaway problem with former Golf diesels (however I did have it with a Hilux 2.2 L series diesel...Had to put her up against a tree to stop her!) After cruisin' the 'net I couldn't find a kit so I decided to make my own.

I just modified my breathing system with great success...That means it hasn't "runaway" since I did it! It's really simple.

1. Buy a couple of feet of heater hose (off the reel), a 13mm plastic irrigation "T" and a 19mm plastic irrigation "T"
2. Cut the hose from the crankcase to the vacuum pump and insert the 13mm 'T"
3. Cut the camshaft cover hose at a convenient point and insert the 19mm "T"
4. Plumb the heater hose between the 2 "T"s

Use hose clips if you must (I didn't) and away you go! After I did the mod (by the way it's basically the same as the official VW mod that you can no longer get) I drove 300km at 100kph and she didn't run away. Before I did the mod. I drove exactly the same route and she ran away 3 times...I eventually had to take another route home via back roads. Since then she's done 3000km with no runaway. All of this running has been done in cool conditions. Whether the mod. would be successful on the mainland in 40 degree temps. I don't know, but the problem seems to be brought on by high engine speeds rather than high engine temps.
Later diesels have a camshaft baffle to reduce oil splash and a screen/filter device on the crankcase breather just to finish the job. I'd like to get my hands on these!

If you'd like to look at a thread on this problem and see some pics. go to:
http://vwdiesel.net/phpBB/viewtopic....er=asc&start=0

But really, to fix it you must rebuild the engine!

Volksfolks · 16-06-2005, 08:11 AM

Great idea man, 'runaway' used to be a problem with my ford escort 1600 deisel mant years ago, that motor was bullit proof!

keep up the good work, cheers Andy

**peter_j_g** · 16-06-2005, 04:02 PM

Thanks for the response and the info!

My car has got the official VW blowby fix fitted, according to VW this was the subject of a recall and all Australian delivered cars should have it fitted.

The problem is that the fix could actually be a little better - the junction of branch pipe from the cam cover to the air filter that goes down to the crackcase is too close to the filter - it should be so that the pipes from the filter and the cam cover run downhill to the junction, and then the pipe from the junction runs downhill to the crankcase - much like you've built. As it is, once oil gets out of the cam cover it just gets sucked all the way to the filter. Once the air filter gets some oil on it and gets a little blocked the the suction is even stronger...

I owned an 85 GTD turbo diesel abroad and I rebuilt that engine - after 365,000 kms - and I remember it having a plastic shroud around the camshaft.

I'll try a new pipe arrangement and see how it works. First I've got to clean out the fuel system to get the car started - I got a bad lot of fuel thats clogged all the filters.

Thanks again!

imported_brackie · 16-06-2005, 05:54 PM

Originally Posted by Volksfolks

Great idea man, 'runaway' used to be a problem with my ford escort 1600 deisel mant years ago, that motor was bullit proof!

I've heard great things about the Escort diesel. What lucky people Europeans are to have such a choice of excellent diesel engines! Wish it was like that here.

**Golf Loon** · 16-06-2005, 06:45 PM

Is the diesel rocker cover the same as the petrol. Later golfs and audis have the shroud over the camshaft, could you use one of these rocker covers?

imported_brackie · 16-06-2005, 07:55 PM

I'm pretty sure the covers are the same. If so, the oil baffles will be too. Anybody got one??

syncro · 16-06-2005, 08:06 PM

Originally Posted by brackie

I'm pretty sure the covers are the same. If so, the oil baffles will be too. Anybody got one??

They used to be cheap from a dealer. You don't know until you ask :!:

20v kit car · 16-06-2005, 08:18 PM

yer phil your right they are cheap from dealers.....who wants one?

imported_brackie · 17-06-2005, 07:34 AM

Yeahdo you have one??, and one of those oil breather filters that go on the hose between the can cover and the air filter box.

**gldgti** · 17-06-2005, 10:23 PM

just before i put new rings in mine last year i made an oil catcher for the rockercover-manifold pipe by using 2 long pieces of heater hose going into a glass jar full of metal pot scourers. there was a long tube inside the jas to the bottom, ( the "in" tube" ) and a short tube that went just inside the jar (out tube). this worked wonders to prevent my air filter elements being saturated with oil, but nothing for crankcase ventilation.

a combination of the two would be ideal...

i never let mine get the runnaway stage very seriously, however it would on occasions like pulling off the highway for a drink (would always shut off if i turned off the ignition).

when we took out the old rings, i was delighted to find no broken ones, just and end gap when in the bore of an astonishing 2.5mm!!!!