Hard Cranking but starter is good?

blazer
starters
#1

I have a gem of a 1994 S10 blazer that is just over 180K. I have done a lot of minor work on the old girl including recently replacing the starter, battery, and battery cable. But the thing is it started cranking really really hard when it is hot about 2 months ago (I replaced the starter over a year ago). But even when it cranks hard it only draws about 200 amps (so the parts guys say the start isn?t bad). Why is this?



Another weird thing: If I punch the gas pedal right as I am turning the key to off it will start pretty normal when I come back.



The last detail. When I took out the starter (to find out the parts guys-es starter tester was broken) and put it back in I noticed the heat shield had broken off. Would this extra heat cause the starter to go bad but not show an over-amp condition?



It started hard/hot when I pulled the coil wire too so I don?t think it is the timing slipping…



:slight_smile:

#2

How do you mean it’s cranking hard? Is it not turning over very fast or is it turning over normally but not firing up readily?

#3

The initial current surge when the starter is engaged may be in the 300 amps or more range for a second and while I don’t know the official recommended figure for a steady current draw on your vehicle, most run in the 125-150 amps range.

JMHO, but 200 amps sounds pretty high to me for a steady current draw with the starter motor engaged so I disagree with these parts guys.

As to the weird part, maybe what’s happening here is that the starter has not had time to heat-soak yet. I would definitely install a heat shield or starter blanket no matter what.

#4

Maybe not related but in the olden days if my timing got too far advanced it made cranking more difficult.

#5

It fires right up but will even stall the starter motor on occasion. The voltage drops way down (like 9.5v) but always fires on the 2nd rotation or so. The book says up to 250 is o.k. for this starter and it doesn?t always pull that hard. This was a test with the coil wire off where it went up to 200a. Normally it is pulling about 150-180 even though it is lugging really hard.

Again 1-year old starter, brand new battery and brand new cable.

But (always a big but) it starts almost 100% normal if you jab the gas right as you are turning off the ignition when you shut it down.

I really don?t want to take the starter out again… It is a real knuckle-buster in this truck.

#6

Heat soak will cause the starter to draw too much current and crank the engine slowly. I had a starter replaced on a 1988 Taurus at Western Auto some years back. The engine would crank very slowly when the car was hot. I took the car back to Western Auto and the service manager claimed that they couldn’t duplicate the problem. In desperation, I went to an independent shop where I had never traded when the car was hot. The technician attempted to start the car when it was hot and measured the current draw. He then disconnected the ignition coil and duplicated his test with the same results. He wrote down the current draw and what he did on his letterhead and told me to take it to Western Auto. He didn’t charge me anything for the diagnosis. When I went back, the service manager at Western Auto didn’t question the findings and immediately had another new starter installed. The best outcome of the whole ordeal that happened 15 years ago is that
I found a great indendent shop and have done business with them since that time.

One other thing is that when you punch the gas pedal as you turn off the the key is that you are injecting raw gasoline into the cylinder. This acts as a refrigerant and cools the pistons so that they contract. This makes the engine easier to crank. In the old days of the carburetor and hand choke, if I made a long climb with the engine near the overheating point, as I descended the grade I would pull out the choke. The over rich fuel mixture would cool the engine and the temperature would be back to normal at the bottom of the grade.

#7

Good to find a good shop. Sadly I still do all my own work on this truck and have for 14 years (Geesch I need to get a life). I am thinking it is the starter/starter bushings. If you bring it home hot it will lug terribly when you try to crank it (no coil in this test). But after the 2nd rotation it spins like a champ with normal draw… even with everything very hot under the hood. Never had anything like this and been working on cars for 25 years. My thoughts on punching the gas at ignition turn-off: First I wish cars were like planes and you shut them down by cutting the fuel (editorial) but I really think this is just pre-charging the cylinders and letting it “catch” one step quicker when I try to re-start it.
I know what you mean about “rich cooling” cylinders but don’t think I could add enough fuel to do this with fuel injection. I have done this in an airplane before with the primer when a cowel flap wouldn’t open.

#8

The fact that you tried disconnecting the ignition to check for over-advanced timing indicates that you know what you are doing so we can dispense with corroded connections and the other easy stuff, except for one thing - did you replace both battery cables? Corrosion inside the insulation of a good-looking battery cable can really cut down current flow.

The missing heat shield could well heat up the starter enough to distort it or increase its internal resistance. The heat shield was put there for a reason. Can you fab one up?

Another thought is a hot spot in the engine due to coolant flow obstruction that is causing a piston to bind in its bore when you turn off a hot engine. That would be unfortunate. The evidence might be a jump in water pressure right after you shut off the car, as water boils at the hot spot. If that is the case, I would pull the water pump and see if the impeller is sound. Perhaps a fresh water pump with a good impeller would move a bit more water and suppress the symptom.

#9

Good point. Does this motor have an adjustable distributor?

#10

I still say the current being drawn by the starter is way too high; and don’t put a lot of faith into what parts counter guys tell you.

#11

Yes I looked at all of the easy stuff. Replaced battery, positive cable, and again the starter is just about 12 months old.

But the odd thing is if you make it past that first “stall” of the starter it will crank and crank at full speed with no hesitation and normal current draw (with the coil off).
No heat problems with coolant temp or ticking after shut down.

I did put the heat shield back on (after hearing it chime down the street behind me one day). It uses a rather small shield not like the wraps we used to use for headers.

Tried it again today and same thing. Everying at normal operating temp. - shut down - first turn stalled the starter- back the key off - next bump of the key it fires up at normal craning RPM (by sound). Water pump has never made a sound since I replaced it at 80,00 and assume it is working… Just pulling my hair out.

#12

The fact the starter is 12 months old means nothing unless it was a brand new, NOT reman, starter. With reman stuff anything is possible.

I put a reman alternator on my Lincoln a month or so ago and it dropped dead 30 minutes later.

#13

I had a friend years ago that had a similar situation and the dealer told him it was carbon buildup in the cylinders due to in town driving, I don’t know if that was a ruse or if it was true how you fix it. Maybe a can of sea foam and going somewhere 120 mph is allowed?

#14

I think it probably does but I have never touched it in 180,000 miles. The car doesn’t “ping” when it running (advance timing problems) and cranks just great after the first “bump” of the key. It also has the same problem with the coil unplugged! So I think I should rule out ignition… Maybe?

#15

I have had bad starters before but they usually just “lug” badly from the first bump of the starter to the last. This is so weird as after the first bump of the key it spins along normally??

#16

Are you using any shims at all? you could try adding one .030 shim. and 200amps is to high.

After all external influnces are eliminated you have to start thinking about a engine mechanical condition.

#17

Again, a steady 200 amp current draw is too high. Dragging starter.

#18

Do fuel injected engines have carbon build-up problems? I thought that was only engines with carbs… But just like the other answers why does this only happen on the first bump of the starter. If carbon was causing an extreme compression situation you would think this would “lug” the starter all the time while cranking. With the coil unplugged it lugs for the first rotation (and bump of the key) the 2nd bump spins the starter like mad and the engine in normal starting RPM until the cows come home.

#19

Yes 200 is too high but it normally cranks at 150. Something is holding it up for the first revolution? After that you can bump the starter all day long drawing only 150 and spinning normal RPM?