06 BRM won't run after thermostat swap

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
OK im stumped. Car is an 06 jetta brm dsg. 170,000 miles. I changed timing belt, cam, deleted egr,changed flywheel and mechatronic unit about 20-30,000 ago. It has been running great ever since. With the last cold snap, it was struggling to get up to temp, so i brought it in for a thermostat change. I drained the water from the lower hose, reinstalled the hose, removed the two oil dipstick bolts to allow it to swing out of the way, removed the alternator ground and power plug ( taped them up to be safe), and finally changed out the thermostat with the kit from idparts along with a new coolant sensor. Reinstalled everything , added coolant back in and started it up. I backed it outside to idle for a bit. I came out, got in the car and tried to rev it up and it starts running rough, smoking white, and wont allow me to rev past 1200 rpm. eventually it dies but it will start right back up and idle and then tarts the process over again. I have scanned with vcds and te only two codes i have are for the egr and intake flap which are removed. I pulled the intake and ran it with the open intake to rule out any suffocation issues. I also checked my torsion value and it sits at a steady .5 in all of the above conditions. What else am I missing??
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
You sure you replaced the correct coolant sensor? Was it the same part number as the one you removed? There are two on the BRM.
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
You sure you replaced the correct coolant sensor? Was it the same part number as the one you removed? There are two on the BRM.
I changed the sensor that goes in the thermostat housing. I bought the whole kit from IDParts. I guess its possible they sent the wrong one. Ill take the old one and plug it back in and see if that changes anything.
 

narongc73

Veteran Member
Joined
Nov 14, 2005
Location
VA/OH
TDI
2006 Jetta TDI
Diesels don't like cold, of course it's gonna struggle to warm up after an egr delete. I have 267k miles on my 06 and the thermostat is still working fine. Don't change a part just because you think it's a good idea. This is what you run into :D
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
Diesels don't like cold, of course it's gonna struggle to warm up after an egr delete. I have 267k miles on my 06 and the thermostat is still working fine. Don't change a part just because you think it's a good idea. This is what you run into :D
I run a trucking company and have dealt with over 50 diesel trucks over the course of my lifetime. My pickup is diesel. My car is diesel. Hell my lawnmower is diesel. I’m well aware of how they operate in ALL temperatures. The car needed a thermostat. Even with the frost heater it wouldn’t get up to temp. So unless you have something useful to add to the subject here please leave the bandwidth to those willing to help.
 

sptsailing

Veteran Member
Joined
Jul 9, 2010
Location
Safety Harbor, FL
TDI
2006 Jetta Manual, stock with Panzer Plate & Franko6 modified EGR cooler & CAM
I am in Florida and have zero experience with diesel engines in seriously cold weather, but your engine's problem is both interesting and quite puzzling, so I have only a very general suggestion. It seems possible to me that the problems you are now experiencing may only be a coincidence and have little or nothing to do with the recent thermostat replacement. My guess is that you may be able to solve the problem if you approach this like it is a problem completely unrelated to the recent thermostat change work. I hope to see your successful solution posted soon. Good luck!
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
I am in Florida and have zero experience with diesel engines in seriously cold weather, but your engine's problem is both interesting and quite puzzling, so I have only a very general suggestion. It seems possible to me that the problems you are now experiencing may only be a coincidence and have little or nothing to do with the recent thermostat replacement. My guess is that you may be able to solve the problem if you approach this like it is a problem completely unrelated to the recent thermostat change work. I hope to see your successful solution posted soon. Good luck!
This is what has been in the back of my mind as well. Atleast it’s in my heated shop on the lift with the exhaust ventilation system on so when it does smoke as bad as it does it’s not fuming me out ?

Let me ask this. Are these symptoms of a faulty fuel injector(s) on these engines? I am much more familiar with my ALH than this BRM.
 

mu3098

Veteran Member
Joined
Dec 29, 2010
Location
Ontario, Canada
TDI
2006 VW Jetta TDI, 2011 VW Golf Wagon TDI
I think the wires going to that coolant sensor run with the wires going to the crank sensor. You might want to check the wires going to the crankshaft sensor.
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
Ok update time.

Still havent gotten anything to change. I hooked vcds back up and ran it at an idle and found the following injector IQ#'s (group 13)

Deviation Cyl. 1 -1.74 mg/str
Deviation Cyl. 2 -1.81 mg/str
Deviation Cyl. 3 2.99 mg/str
Deviation Cyl. 4 -1.72 mg/str

Looks like im pulling the valve cover and looking for anything obvious before looking into new injectors?

**Also group 1 shows Injection Quantity Climbs the longer the engine runs. It seemed to level out at 15.4 mg/str at idle. When giving it throttle it spikes to 26 mg/str and starts shuttering and dies.
 
Last edited:

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Been running great, but obviously not now, and how it is running now is what prompted you to make this thread, yes?

You clearly have a dead cylinder, as evidenced by the compensation numbers you gave. The most common reason on a BRM is a bad cam. Injectors rarely outright fail, but it is certainly possible. Also possible you have a bad connection in the injector harness in the head, which is at least an easy item to swap on the transverse cars.

I do not know what this would have to do with a thermostat change, but as suggested by someone else earlier in this thread, sometimes if nothing obvious related to the work just done pops out as a cause, then it is best to go into it with a fresh look.
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
Been running great, but obviously not now, and how it is running now is what prompted you to make this thread, yes?

You clearly have a dead cylinder, as evidenced by the compensation numbers you gave. The most common reason on a BRM is a bad cam. Injectors rarely outright fail, but it is certainly possible. Also possible you have a bad connection in the injector harness in the head, which is at least an easy item to swap on the transverse cars.

I do not know what this would have to do with a thermostat change, but as suggested by someone else earlier in this thread, sometimes if nothing obvious related to the work just done pops out as a cause, then it is best to go into it with a fresh look.
It sure seems like something that was bumped while it was in the shop. Injector harness possibly but im not ruling anything out at this point.
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
Another update. Just pulled valve cover and all is well with the cam and lifters. I checked the injector harness for continuity and resistance and it is in great shape. All #’s are perfect. Next I will set everything to tdc and check timing. But that doesn’t explain my horrible IQ #’s.
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
And hooked vcds back up today to get readings again. The first series is dead cold start

group 1- idle speed 861- injection quantity 15.4- injection duration 9.2 KW - Coolant temp 15.3C

group 4- engine speed 840- injection start 6.8* BTDC- inj duration 9.2*kw- torsion value 1.0*KW

group 13 - cyl. 1 0.56 mg - cyl. 2 -0.66 mg - cyl 3 -0.56 mg - cyl. 4 0.66 mg

And this series is after 2 min run time, almost to the point of stalling

group 1 - engine speed 798- injection qnty 22.5 mg - inj duraton 9.7*KW coolant temp 29.7*c

group 4 - engine speed 798 - inj start 10.5*BTDC - inj duration 10.2*KW - Torsion value 1.0*KW

group 13 - cyl. 1 -0.92mg - cyl. 2 -2.38 mg - cyl 3 2.99 mg - cyl 4 -2.00 mg

sorry for typing it out. Im not yet familiar with uploading pics
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Looks to me like an injector is heating up and going bad. Assuming you have no plumes of white smoke in the exhaust that would indicate fuel but no combustion (like poor compression) but compression really shouldn't be fine when cold then go away to the point of misfiring when warm.

Cylinder 3 is the one suspect, it is basically maxing out the fuel quantity and it isn't enough. The values look picture perfect when cold, though.
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
It does smoke as it gets worse. Heavy white. How do you feel about group 1 injection quantity from 15.4 up to 22.5? Im not sure if that # is relative to my issues?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Ok, so that DOES suggest possibly a lack of compression.

I would warm the engine, shut it off, remove the plugs, unplug the injector harness on the head, and do a compression test. At least just to rule that out.

Not sure why it would change that dramatically cold to hot, unless a valve or lifter is somehow messed up and the expansion puts it just over the edge.

You have no loss of coolant? The smoke is white-blue like oil or unburnt diesel and not a misty sweet cloud like coolant, correct?
 

BigB82789

Well-known member
Joined
Oct 1, 2014
Location
oh
TDI
jetta
Yes it is a very fuelly smoke. I will have to warm the engine with the frost heater since it wont run long enough to get to temp. Just seems so weird that it pulled in the garage running perfectly and now this. Oh well.
 
Top