Runaway truck! Breather mod questions...

[veeman]

Last night I finally got to drive my caddy after replacing the engine with a 1.5L that I got from a friend.

I had heard about the "runaway" problem from this board and a few other sources, but last night, I got to experience it first hand.  The truck was running fine around town, so I decided to take it on the highway to see how it would cruise.  

After accelerating in third to get to highway speed, I was rattling along at 55-60 mph when I saw a big plume of grayish smoke out the back and the engine began accelerating like never before.  Runaway!  Whoa.  Wild.  I got off at the next exit and luckily, the problem stopped at the end of the ramp.

Anyway, I know that this is caused by oil (blowby) coming from the valve cover breather being dumped directly into the intake.  Obviously this engine has some miles on it and probably needs some rings, but for now I wanted to see how to control this.  

Here's how the hoses are run right now...




My engine does indeed have the "cam saver" tray in the valve cover, but obviously that's not preventing the problem.  I think that the previous owner had tried to install a breather mod on the engine to help control this behavior. When I got the engine, this wasn't installed, so I want to make sure the following routing is correct:



He used a spare coolant reservoir tank and routed both the vent from the block and the valve cover breather to it.  He drilled the side of the tank to make room for hose 2.  

I would imagine that his thought was to have the valve cover hose dump into the reservoir via hose 2 so that it would "precipitate" and drain back to the block via Hose 3 while the vapors went back to the intake via hose 1.

What I'm not clear about is the function of hose 4.  It's a small diameter hose (~1/2 inch) attached where the thin overflow hose to the radiator would nornally go.  Could this purely be a vent for the system to draw in clean air?

Also, I'd like to know whether or not the inlet to the vacuum pump in this scenario is simply open to the atmosphere and if that's a problem (for noise or other reasons).

[fspGTD]

If the engine ran away with these mods, the engine probably has lots of blowby and likely needs a rebuild.  Venting the crankcase and cam vapors directly to atmosphere may be necessary.  If this is done (IE: cap hose 1, enlarge hose 4), they should not also be connected to the intake at the same time (IE: leaving hose 1 and hose 4 = bad idea.)  The reason is you don't want to allow a path for dirty air to get into the intake bypassing the air filter.  But warning, unfiltered crankcase vapors smell really bad.  :?

I can't see how the open vacuum pump connection would make a problem - since air is exiting the vacuum pump there, it shouldn't (at least in theory) make a problem with dirt entering the pump.  Venting it directly to atmosphere like that should also cut down on the volume of air flowing through the crankcase vent system.

[veeman]

>> If the engine ran away with these mods, the engine probably has lots of blowby and likely needs a rebuild.

Actually, I haven't installed the setup in the second drawing.  When I installed the 1.5, I left the hose routing like diagram 1 for simplicity's sake.  I plan to try the PO's breather mod soon, I just wanted to make sure I had the routing correct.

The bad part is that I have zero idea how many miles the 1.5 has on it, so I'll just have to watch the oil consumption or get a compression tester to tell.

So, from what I understand, the "runaway"  problem mostly happens at high rpm's at highway speed because more oil is atomized under those circumstances.  Can I assume the smoke was grayish-white because the engine was burning oil, not fuel?

[fatmobile]

I think the reason the 1.5 would runaway, was the oil return hole is too small.
 All the crankcase gasses are racing toward the valve cover outlet and no oil can run back to the crankcase, it gets pushed along and into the intake manifold.
 The 1.6s had a larger oil return and runaways are rare.
 VW made a hose for the 1.5, that goes from the valve cover outlet to the block ... where your vacuum pump is supposed to dump to.
 I don't think all the other stuff is necissary. It just needs another path to return oil to the crankcase.
 There is a recent post on here, where a guy made his own, pictures and all.

[veeman]

>>I think the reason the 1.5 would runaway, was the oil return hole is too small.

Do you mean the return holes in the head under the valve cover?

>> I don't think all the other stuff is necissary. It just needs another path to return oil to the crankcase.  There is a recent post on here, where a guy made his own, pictures and all.

Do you remember what the subject was or who posted it by chance?

[veeman]

Hmmm...  Maybe this is it.

http://vwdiesel.net/phpBB/viewtopic.php?t=1086

I also found reference to an industrial alternative that's available as well.  Seems like it might be pretty expensive though.

http://www.mann-hummel.com/industrialfilters/index.html?iKeys=22.1.252.1.1&cScr=75&v_pbid=9&v_pid01=44

[toomanycars]

I don't think all the other stuff is necissary. It just needs another path to return oil to the crankcase.
 

I've 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. A while ago I drove exactly the same route and she ran away 3 times...I eventually had to take another route home via back roads. I'm still trying to get the camshaft baffle and a screen/filter device that I've seen on the crankcase breather just to finish the job. (Any offers???)

[veeman]

Just a quick update...

After looking at pics of VW's fix for the runaway problem and reading toomany's suggestions, I took a trip to Home_Cheapot and picked up some supplies to make my own "Y" hose.

I ended up buying some 1/2 inch diameter copper T's  to make the unions (water pipe application, I'd guess).  When I first saw the T's, they appeared to have a bead on the ends, making me think it was for a hose type application, but after closer inspection, I found out they have "built-in solder" on the inside of the bead.

Apparently, you can put a straight piece of pipe into it and then heat the joint from the outside and it solders internally. The bead helps keep the hose on and although the solder is not necessary for my application it's still a neat idea.  (Check it out...   http://www.grainger.com/Grainger/productdetail.jsp?xi=xi&ItemId=1613540009&ccitem= )

Long story short, I used some 5/8" hose and put in a T at the valve cover hose location (Hose B in the first drawing above) and at the block breather location (Hose A).  I was able to use the stock hose (Hose A) to keep the 90 angle just before the intake and connect it to one side of the T.   It all turned out pretty well.

I took it out for a test drive at speed and all seems well.  The truck seemed quite content to buzz around like it should...fueled only by the diesel fuel as intended.  No runaways thus far!    It seems as though the PO's idea using a spare coolant tank would have worked, but this solution takes up less space and is considerably more compact.  

I can post some pics if anyone's interested...

[fspGTD]

Nice... those copper tubes with the built-in beads are cool stuff... thanks for the heads-up on them.  Also, let us know if it solves the problem for good after some more longer term testing?

I ordered a MANN provent for dad's Rabbit.  Not cheap at about $150 shipped, but should be an interesting experiment.  From what I read about them, they are effective in stopping blowby oil.  I am going to try running the provent venting directly to atmosphere and see if it filters out the usual stinky blowby smell.

[toomanycars]

Hey, Veeman! Glad it worked for ya! My plastic fittings have been fine so I'll only use copper if they become distorted from heat. But yes, it's definitely fixed the runaway problem ....at least on the runs that i've been doing.

[Deadeye]

I had that problem years ago, (before rebuild) and the rerouting of the vents work for a while, and that MANN provent is new to me, but looks great.

When I finally did disassemble the engine. I did a quicky ring job. It only lasted 10,000 miles. I took it apart again and paid closer attention to what was going on. The piston skirts were worn ( around .010 under standard), but the cylinder walls were in fairly good shape. There was hardly a ridge at the top of the cylinder. I went ahead and overbored it, but in a pinch, I bet just a set of new pistons would have gone a long way.

[Caddy-Daddy]

I just had the runaway problem last week.

My engine overrevved on the highway, lots of black smoke and finaly it died.When removing my intercooler I noticed it was almost full of oil. Poured a litre out of it. (pic will follow)

Í'm in the process of replacing my JR engine (similar to the MF) with an Eco (1V) as I could get it really cheap.

Just swapping the fuelpump, and the K24 Turbo to the 1V. Is it true that the 1V doesn't have oilsquirters? and are there other things that I have to be carefull with?

[DieselMonkey]

I pulled the pan on my 1996 /7 1.9D, 1Y engine and found a complete TD short motor. Pistons, squirters etc... So i would say its very possible you will have them. More likely if the part number for the cylinder head is 028 103 373 J .... its in the top left of the head, above injector no.1.

hope this helps. DM

[Caddy-Daddy]

I pulled the pan on my 1996 /7 1.9D, 1Y engine and found a complete TD short motor.

Are you sure? because I'm referring to the 1V which is a 1.6L  engine with K14 Turbo.

But thnx DieselMonkey for the info..  I will check the numbers on the head.

Let's hope the squirters are there..  

Here's a pic of what came out of my intercooler...

[veeman]

I finally snapped some pics of the breather hoses and T's I made to stop the runaway problem...

Here's the valve cover to intake hose setup.  The stock hose fits quite nicely in with the T and even preserves the 90 degree bend at the top near the intake...




Here's the lower hose that T's in between the block vent and the vacuum pump.  The pic's a bit out of focus, but I think you'll get the idea...




Been driving the 1.5 for quite a few trips and still no runaways.  The  only issue I had was that the bottom hose going to the block was loose and caused quite a mess when the return oil dribbled out instead of going back to the pan.

Hope that helps.