Hard start... where too next?

Technical questions and answers concerning all models of VW diesel vehicles.

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greg lousy
Turbo Charger
Posts: 230
Joined: Thu Apr 05, 2012 12:22 am
Location: Rhode Island

Hard start... where too next?

Post by greg lousy »

Jetta started starting real hard about a week ago, as in barely making it on its own battery or needing a jump. Ive been tooling with this for a while and im not sure where to go next.
It had been starting hard and i got through the winter mostly with my truck, then when it got warm enough for outdoor work i went at the jetta pretty seriously.
Checked and slightly advanced timing, new injector nozzles, took out that water seperator thing, replaced starter and cleaned a bunch of connections. Compression test - mid to high 300s, i know, not great but it should start up ok at like 50 degrees right? Visualized glow plugs, all good (manual button - bypassed relay). Clear lines... no air or maybe like one tiny bubble in return hose after sitting and none running.
Ive been doing ok in these hard start/ no start scenarios. My problem now is that ive pretty much gone through the steps and checks that have always lead to success. ... no success.
It was starting pretty good after i did the starter and nozzles for a few weeks till recently, so that tells me that the ip timing and injector rebuild was at least ok. Good crank now too.
IP feels good to me too. The cold start cable gets sucked back in real good, IP pully runs dead straight. Double checked general timing when i tweaked ip, and ive tried a few different positions, all around the high end of spec. And like i said, no air.
Car runs good, some black smoke when accelerating
I havent checked fuel pressure, maybe next. Maybe tweak IP again but i feel like im in a good spot, and it started there recently. I have already gone in once thinking i slipped a tooth and found i did not. Exhaust manifold/ turbo area isnt air tight - smoke from there at start up.
I bottle fed it once too, started just as hard.
Im missing something and im hoping that thing pops into someones brain here cause mine's about empty.

Other info... been burning oil, turbo sounds and feels ok.
Various vehicles in various states
wmasscaddy
Cetane Booster
Posts: 83
Joined: Tue Jan 24, 2006 10:00 pm
Location: northampton,ma

Re: Hard start... where too next?

Post by wmasscaddy »

Two unexpected things that gave me hard starts:
1) Needed a new air filter
2) Ignition switch didn't open solenoid WHILE cranking. Put a jumper to solenoid. Replaced ignition switch.
82 pickup 1.6 n/a
350,000 + miles lost to broken odo
11mm block, 12mm head
greg lousy
Turbo Charger
Posts: 230
Joined: Thu Apr 05, 2012 12:22 am
Location: Rhode Island

Re: Hard start... where too next?

Post by greg lousy »

Thanks, that was actually helpful. Newish air filter and i think i tried starting with the air filter off, but i got to thinking about air and i have an air intake problem.
My other vws were all NA and this is the first turbo vehicle of any kind ive had. I get the basic idea of turbos but im a turbo amateur. Maybe someone can enlighten me. I disconnected air intake and the main turbo to intake connection and started the engine NA style. .... much better.
Turbo spins freely by hand. Not sure if air pressure relief valve is working... the hose going to it blew out at some point. I fixed it but now im wondering if it blew out for a reason.
All i really know is that the car starts with the turbo to intake bypassed. Maybe someone can shed light. Always apprecciated
Various vehicles in various states
TylerDurden
Turbo Charger
Posts: 1285
Joined: Tue Dec 22, 2009 1:01 pm
Location: Michigami, USA

Re: Hard start... where too next?

Post by TylerDurden »

I'm not too sure the intake or turbo are the root of the problem.

I'd try putting a switch inline instead of a button on those GPs... the stock relay keeps them on during cranking and about 20 sec after.

What weight crankcase oil? Slow cranking is a significant issue with lower compression.
Have a nice day.


'91 Jetta ECOdiesel TD - clean & complete (less motor/tranny) for sale

'82 Westy Vanagon 1.9 N/A - 23.5mpg
'86 Jetta TD - 45-50mpg
'81 Dasher Wagon 1.6 N/A - 52mpg
'84 Wasserboxer - DOA, parts donor
'94 Passat wagon VR6
'03 Jetta TDI wagon 230K, 52.3mpg
'89 Jetta N/A - 51mpg
'82 Caddy 1.6 N/A - Sold
greg lousy
Turbo Charger
Posts: 230
Joined: Thu Apr 05, 2012 12:22 am
Location: Rhode Island

Re: Hard start... where too next?

Post by greg lousy »

15w40.

Looks like i was probably wrong about the air. More shiybstarts/ no starts. Sometimes it starts fine and throws me off.

Turbo basicaly works when running. Is there any possible fail that would cause air problems when starting or should i stop thinking about this?
I definitely have blowby and i understand that im probably getting less actual compression than when i tested and had all injectors out and a fast crank. Sometimes it starts right up and i suspect that i get less compression after the first fast cranks and if i miss this window things get ugly.
Whats grinding at me is that my golf definitely had worse compression/ more blowby and started much better. Of course i had a better crank on that car. I dont know what i would do for a better crank. Newish battery that charges fine and reads what it should volt wise anyway. New starter. New statyer bushing.

Smoke tells me fuel solenoid working.
Ive had glow plugs on a button on all my vehicles i keep pushed while cranking and after on real cold days. Im fairly confident about glpw plug operation. Ive used a switch before but i left them on accidentally a few times and went with the button.
This car is at the end of life in the northeast and will not be worth engine repair. Rot. Basically trying to cheat death while i figure out my transportation.
Open to short term sketchy ideas lol.

Maybe its just the crank/ compression factors and im just driving myself crazy working on other solutions.
Would lighter oil really help crank that much?
Various vehicles in various states
Fatmobile
Global Moderator
Posts: 7564
Joined: Wed Oct 30, 2002 10:28 pm
Location: north central Iowa

Re: Hard start... where too next?

Post by Fatmobile »

It was mentioned that sometimes there is voltage to the pump,.. until you hit the starter.
Not a real common problem but it does happen. Often an intermitent problem related to a bad ignition switch.
Check the voltage at the pump with starter engaged.

Your first post was a great list of all the things you should check and mess with when the car starts hard.

Have you tried turning the crank over by hand to check compression?

Fuel moving in the clear line? ,...I don't think the vane pump would suddenly go out but had to ask because it almost starts on the first try when the fuel isn't moving.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
greg lousy
Turbo Charger
Posts: 230
Joined: Thu Apr 05, 2012 12:22 am
Location: Rhode Island

Re: Hard start... where too next?

Post by greg lousy »

I did compression test when i had the injectors out and got mid 300s to about 400 with cheap harbor freight tester that i think would read low if anything.
When you say voltage to the pump you're talking about fuel solenoid, right? So far ive been at this 100% solo so i havent been able to do any testing in the engine compartment during the crank. Maybe Ill try a little jumper to rule this out.
Havent been able to look at fuel line while cranking either. Last few days its been starting fine when warm... using the block heater in friggin May
Various vehicles in various states
Fatmobile
Global Moderator
Posts: 7564
Joined: Wed Oct 30, 2002 10:28 pm
Location: north central Iowa

Re: Hard start... where too next?

Post by Fatmobile »

If you get a chance, try turning over by hand.
Even though I agree a compression tester is more likely to read low and your numbers are fine.
It should fight you and try to turn backwards near the top of the stroke.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
greg lousy
Turbo Charger
Posts: 230
Joined: Thu Apr 05, 2012 12:22 am
Location: Rhode Island

Re: Hard start... where too next?

Post by greg lousy »

I removed the plunger from fuel solenoid. Ruled that out, same starts.
Turning the engine by hand felt wrong. It seemed much too hard to turn between compressions. Some strokes felt ok.
I was about to swap IP to see what happens but stopped when I felt that. Dont really like the look of things.
Various vehicles in various states
Fatmobile
Global Moderator
Posts: 7564
Joined: Wed Oct 30, 2002 10:28 pm
Location: north central Iowa

Re: Hard start... where too next?

Post by Fatmobile »

You can tell alot by turning the engine by hand and getting a feel for it.
What do you think the problem was?
Did it try to turn backwards/pushback?
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
greg lousy
Turbo Charger
Posts: 230
Joined: Thu Apr 05, 2012 12:22 am
Location: Rhode Island

Re: Hard start... where too next?

Post by greg lousy »

More like constant resistance where it should have turned easier. I think it could be a few things and probably in the engine. Even if whatever it is causes no other problems, the amount of energy needed to turn the engine probably explains the hard starts. I did my first ring job on this car about 3 years ago. Felt ok about it, but maybe i screwed something up there.
Car has rot issues, not sure what the future is for car or engine
Various vehicles in various states
TylerDurden
Turbo Charger
Posts: 1285
Joined: Tue Dec 22, 2009 1:01 pm
Location: Michigami, USA

Re: Hard start... where too next?

Post by TylerDurden »

greg lousy wrote: Sat May 05, 2018 1:08 am More like constant resistance where it should have turned easier. I think it could be a few things and probably in the engine. Even if whatever it is causes no other problems, the amount of energy needed to turn the engine probably explains the hard starts.
For the resistance check, you might pull out the vacuum pump... it has some resistance and also drives the oil pump.
Have a nice day.


'91 Jetta ECOdiesel TD - clean & complete (less motor/tranny) for sale

'82 Westy Vanagon 1.9 N/A - 23.5mpg
'86 Jetta TD - 45-50mpg
'81 Dasher Wagon 1.6 N/A - 52mpg
'84 Wasserboxer - DOA, parts donor
'94 Passat wagon VR6
'03 Jetta TDI wagon 230K, 52.3mpg
'89 Jetta N/A - 51mpg
'82 Caddy 1.6 N/A - Sold
bscutt
Turbo Charger
Posts: 1720
Joined: Mon Mar 10, 2003 4:49 pm
Location: Springfield, VA

Re: Hard start... where too next?

Post by bscutt »

Are you sure you are getting good voltage to the starter? You could have some corrosion building in the battery cables which would reduce voltage to the starter under load. One trick I have done is connecting a good jumper cable from the battery negative terminal to the engine block which would reduce voltage drop in the ground cable. Doing the same to the positive cable gets dicey since getting a jumper cable clamp on the starter positive stud means potentially arc welding/fire. BTW cables can look fine but have corrosion down inside the insulation you can't see. It's worth doing some experimentation in that area.
Otherwise it seems like it should start even with compression in the 300's. My 82 is in that region but starts even when cold although one cylinder is bad until it runs for 20-30 seconds. Hope it stays that way for a while. Just did new paint 3 months ago then got hit by a deer 2 weeks ago, just enough damage to irritate the ^&*% out of me. Such is life.
Bob

'06 Jetta TDI
'82 Rabbit 1.6NA
Honda, 99 GMC Suburban, '41 Chevy Coupe
greg lousy
Turbo Charger
Posts: 230
Joined: Thu Apr 05, 2012 12:22 am
Location: Rhode Island

Re: Hard start... where too next?

Post by greg lousy »

Ive had a good extra ground on a starter bolt this whole time. Think its a 6 or 8 gauge right to negative terminal, extra one to chassis too, and original one to the trans. Checked/ cleaned positive starter cable terminals at some point. Maybe ill try a different cable or look at the cable itself at some point but im still thinking theres a problem causing it to take way too much energy to turn engine. Sorry about the deer... no respect for classic vehicles.

I plan on removing vacuum pump at some point. Isolating as many moving parts as i can. Ill remove the head if i have too. Suspect something in the block. Engine probably could have used a rebore instead of just rings.
This being said, ive got other transportation (actually my buddy's mk2 golf with a vr6 swap i was helping with.... driving like a different type of vw guy... feel a little like a fraud.... getting places quickly though!)
I have a few priorities before this jetta, and theres other problems... no 5th gear, drivers side very rotted... not just pans, subframe. Electrical probems. I may see if anyone wants to take this off my plate.
Anyone here can pm me if interested, now that ive talked up the car so well, lol.... did i mention its a Wolfsburg edition?
If not, then i will definitely get to the bottom of this and let you guys know, even if its just to get an answer. This has become personal.
Various vehicles in various states
bscutt
Turbo Charger
Posts: 1720
Joined: Mon Mar 10, 2003 4:49 pm
Location: Springfield, VA

Re: Hard start... where too next?

Post by bscutt »

Yep hopefully not a broken ring or something seized up. As for the fun to drive gassers my son has an 87 Golf with a G60 conversion, coilovers, disk brakes all the way around, it'a blast and faster than his G60 Corrado. But due to rust issues it is becoming an engine donor for a pristine 85 Rabbit convertible which should be even quicker with 300 pounds less weight.

Anyway keep digging. It's a real pain to have to take off pieces one by one to troubleshoot/isolate but that's often whats needed. If my 82 gets that way I might have to go find a nice 1.9 TD to stuff in there but time for projects keeps going away. Such is life. Hope to retire some day and get back to something fun.
Bob

'06 Jetta TDI
'82 Rabbit 1.6NA
Honda, 99 GMC Suburban, '41 Chevy Coupe
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