Question about diesel start-stop

sparksdc · Post by **sparksdc** » Wed May 16, 2007 8:42 am

Since this is my first diesel and it just made it on the road about 1 week ago I have a general start-up question.

Do diesels need to sit for a bit before restarting warm?

When I first start it cold, it fires right up. Shut it off, put a few gallons of diesel in, start it warm-takes a bit more to turn over. Got curious, so I parked in the driveway after it ran for a half hour in 65 degrees, turned it off, then tried to start it immediately. Starter ground for about 10 seconds with no fire up, so left it off.

Car sat for 13 years, I replaced the rubber fuel lines, had the IP resealed, changed oil and filter, changed fuel filter, new glow plugs with current. There is a little oil seepage between the head and the block in between the #2 & #3 cylinders at some point when running, I haven't caught it actually happen yet. No unexplained coolant level drops or any coolant in the oil or oil in the coolant. Sure I'll need to replace head gasket at some point, but searching posts here said that without contamination, it's not an immediate deal.

Advice and thoughts appreciated.

libbybapa · Post by **libbybapa** » Wed May 16, 2007 9:25 am

I don't see the timing belt on the list of things replaced. DO NOT RUN THE CAR UNTIL THE TIMING BELT IS REPLACED. After 13 years of sitting, that belt could go any second and it's somewhat surprising it hasn't. If the belt goes the pistons will hit the valves and your engine will be ruined. Replace the tensioner while you're at it.

The diesel should start easier when warm. I have a feeling that your starter needs to be removed, cleaned, lubed and replaced and the electrical connections cleaned up.

The oil seepage between 2+3 is the headgasket. That is where the pressurized oil flows up to the head. Often if they sit the rubber will dry out there and leak (more testament to replacing that timing belt). Unless you are concerned about the mess, it's not a problem until it's a gusher.

Andrew

sparksdc · Post by **sparksdc** » Wed May 16, 2007 9:47 am

Forgot to mention timing belt and alternator belt replaced

Had fun timing for the first time but runs well.

The positive battery lead to the starter also looks a bit odd-not grease but some discoloring. Also a source of problem?

Could you explain why the starter would work better cold than hot? Just for my own learning curve.

VWCaddy · Post by **VWCaddy** » Wed May 16, 2007 10:46 am

Anything different when you try the warm start in how the starter operates? Like does it crank over slower? Might be a combination of the possibly higher compression in the warm engine due to the easier flowing oil making it harder for the starter to spin the engine over. Also, check and clean all the power and ground connections. On my '82, that I recently got running again, had starting problems and ended up adding an extra ground cable from the chassis to the engine block. In my case, the painted transaxle and tranny mounts that I put back in must not have allowed enough metal-metal contact for the normal ground path to function well.

Vincent Waldon · Post by **Vincent Waldon** » Wed May 16, 2007 12:44 pm

Couple of random thoughts:

- Heat soak can actually make a dodgy starter much more dodgy.. saw it millions of times back in my Beetle and VW van days. Heat soak is generally not a problem with the watercooled VWs given where the starter sits, but I have heard of it happening at least once.

- when it's warm the glow plugs will not come on. If the compression is poor this will lead to starting problems, even with a somewhat warm engine... nothing like spraying fuel directly on a red hot glow plug to get a diesel's attention. Perhaps the next time this happens jump the glow plugs for 30 seconds and see if it reacts better.

tawney · Post by **tawney** » Wed May 16, 2007 2:43 pm

One other possible contributor to the problem: how did you set the timing on the injection pump? If it's too advanced, it would assist cold starting, but adversely affect warm starts.

However, my money's on the starter being too slow; I have twice taken Andrew's advice about cleaning and lubricating the starter: it makes a huge difference in rotational speed and ease of starting.

sparksdc · Post by **sparksdc** » Wed May 16, 2007 7:21 pm

Cranked it a few times when I got home-definitely slower after the first round. Will take the starter off and give it the whatsover and see if that helps.

When I timed the beast, I retarded it just a bit from original-supposed to reduce emissions when using biodiesel & WVO-we'll see when it's dependable.

Thanks for all the advice. Wouldn't even be out of the driveway without this forum.

jkeiffer_gearhead · Post by **jkeiffer_gearhead** » Thu May 17, 2007 1:14 am

I just got my rabbit TDI running and I was having the same issues with a brand new starter, but if I put jumber cables from the positive battery post to the starter positive it would crank fine when warm, I then replaced the positive battery cable with a 2 or 4 guage, I cannot remember, but now when I hit the key I cannot get off the key before the engine is at idle, it starts incredible

later
Justin

Post by **Fatmobile** » Thu May 17, 2007 2:20 am

The glow plugs don 't come on when it's warm.
Unplug the sensor before a hot start and wait awhile for the glow plugs to cycle.
The glow plug light will stay on too long when the sensor is unplugged so see how long it stays on cold and wait that long before turning the key.
If it fires right up hot, after a glow cycle that could mean low compression.

MPalm · Post by **MPalm** » Thu May 17, 2007 4:14 am

I had a -86 Golf 1.6N/A for 5 years ago and it was hopeless to start when warm. If i tried to start immedeatly after stopping, it fired right up but if it sat for 5 minutes or so it just wouldn't start within 30secs of cranking

I sold it to a friend who bored and reringed it and then the problem was solved...

sparksdc · Post by **sparksdc** » Thu May 17, 2007 8:33 pm

Update

Took off the positive battery lead from starter-ran to get a replacement just in case. Local parts store didn't have one so brought it back home. Reconnected everything and thought I would try the jumper cable trick above.

Ran it 20 minutes, stopped and shut the ignition off. Turned the key just to see before I did the jumper cable-started right up, 3 times in a row. Tried a few hours later, same thing-starts right up no problems now. Must have been the connections.

Of course my brake light just came on....

A1-2-A3 · Post by **A1-2-A3** » Sat May 19, 2007 10:56 pm

On my 79 I had that brake light and oil light on the bottom LHS of the warning lamps. The seatblet light was on as well. I got sick of fixing electrical problems on the car and I pulled all the bulbs and put a oil pressure guage in. The way that cluster is wired is crazy and makes not much sense, many lights shared a common ground and when one was acting up everything would screw up. Damn VW for thier wiring, but what can one expect for old clunkers! The only things that matter is the 12v to the fuel stop solenoid, the headlights and blinkers, the rest is all add on luxury. How can you tell my car was never saftey certified! But with enough head scratching you can fix all your problems. I used to grab two sets of booster cables and start clamping various parts on the engine and chassis untill my problems were fixed then i would run ground wires where I needed to remedy the problem. 9 out of 10 it was always the grounds.