SR20DET swap first start problems

Problems, ideas and comments specific to engine swaps.
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Ottawa510
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SR20DET swap first start problems

Postby Ottawa510 » 21 May 2014 20:22

I have swapped a SR20DET into my 510, and am having trouble starting the car for the first time. I bench tested the starter and both the solenoid and the motor work. Once installed, the starter clicks once when the ignition is turned to start, and once again when I stop pushing the key to start, so the solenoid is working. Also, the crank turns slightly each time, so there is rotational force from the starter motor. I am trying to figure out why the engine won't turn over, and I have come up with the following possibilities, which I intend to test one by one:

- battery too weak to turn over the engine (it's about 6 years old)
- battery to starter connection too weak to provide proper current (battery has been relocated to trunk, longer transmission line)
- engine seized and doesn't turn (although it seems to turn a little each time the starter is activated)
- ignition does not hold the current to the solenoid, it only provides a pulse (ignition was replaced with new unit)

Does anyone have any ideas as to why the starter is clicking only once and not turning the engine?

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okayfine
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Re: SR20DET swap first start problems

Postby okayfine » 22 May 2014 06:02

I think those are all the checks that would be initially suggested. Maybe also put a wrench on the crank pulley to verify the engine turns freely. Battery or connections would be Suspect #1.
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

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defdes
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Re: SR20DET swap first start problems

Postby defdes » 22 May 2014 07:19

All well grounded?

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Ottawa510
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Re: SR20DET swap first start problems

Postby Ottawa510 » 22 May 2014 17:34

Thanks for the tips. I can't turn the engine well as the radiator and fan is in the way. I checked the battery and it is 12.4V, so on the low end of good, and the solenoid voltage when the key is in start is 2.5V, less than 12V but something nonetheless. I will check grounds now, and otherwise dismantle the cooling setup to turn the crank. Any other ideas while I am at it? Thanks!

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Ottawa510
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Re: SR20DET swap first start problems

Postby Ottawa510 » 22 May 2014 20:34

The signal to the solenoid is 2.6V, and deteriorates over the first few seconds. Is this right? Should the voltage be 12V? And should the voltage remain constant while the key is in the start position? I checked the wire connections and they are good.

I grounded the starter separately and no change The engine is properly grounded to chassis by the intake manifold. I have removed the radiator fan and will turn over the engine tomorrow to make sure that is smooth.

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okayfine
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Re: SR20DET swap first start problems

Postby okayfine » 23 May 2014 06:12

Solenoid voltage at 2.5V isn't going to do anything for you. How are you measuring this? 12V+ from the battery should be connected to the solenoid lug. If you're measuring at that lug, then there's an issue through the cable. If you're measuring on the other lug (that the solenoid jumps to) then there's a problem in the solenoid. But you mentioned you tested it off the car and it worked.

Voltage dropping off could be a sign of a short/resistance increasing due to inadequate connection.

Can you pull the battery out of the trunk and safely jump the starter with a lead across both solenoid terminals? I know an SR install gets tight around those quarters. That would eliminate your cable routing, and definitely supply full power to the starter.

Also, a battery showing 12V via a VOM may well drop off a cliff once you apply a load to it. Do you have a known-good battery you can use for testing? Or get your 510 battery load-tested?
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

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Ottawa510
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Re: SR20DET swap first start problems

Postby Ottawa510 » 23 May 2014 07:45

The battery cable to solenoid lug is showing +12.2V. The thin solenoid signal wire from the ignition is at 2.5V, but that is while the solenoid is actuated (key to start). I figured the solenoid puts a load on the signal wire (hence voltage drop) but it is actuating, so should also connect the battery to the starter motor through the main solenoid lug. I can try jumping the solenoid wire from the battery, as you suggest. I was going to try a portable jump starter since I don't have easy access to a good battery, as all are in vehicles. I'm also going to turn the engine over a few times tonight since I dismantled the fan.

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okayfine
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Re: SR20DET swap first start problems

Postby okayfine » 23 May 2014 09:28

There isn't anything in the 510 ignition circuit that cuts power to the starter wire. It should get full battery voltage through the switch.

I expect you'll be able to jump the starter successfully. Do you have a wiring diagram for the 510?
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

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Ottawa510
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Re: SR20DET swap first start problems

Postby Ottawa510 » 23 May 2014 09:47

I have a wiring diagram I was working off. If the next set of tests doesn't work, I will trace the wires from the battery to the ignition, to make sure that connection is good. However, that's an original connection and it worked with the L18 previously.

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andrew.lori
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Re: SR20DET swap first start problems

Postby andrew.lori » 23 May 2014 12:36

Don't pull the cooling system to turn the Engine by hand.
Put the car on the ground stick it in gear and push it back and forth the engine should turn. If not you have bigger issues.... :(

Signal at 2.6V please confirm if this is while turned to start position.

Have you Jumped the starter from the positive terminal to the Solenoid that will confirm if the cars wiring is the issue
You can also short the starter Directly to positive .It will spark a bit but again you will confirm if you have a starter issue.

Oh YA I still can't find my spare starter for you to try.

Andrew
1966 Sunbeam Tiger MK1A
1970 Datsun 510 CASC Road Racer ( to be restored )
1972 Datsun 510 SR Monster Sold it
1977 Datsun 200SX
1973 Toyota Celica
1972 Triumph GT6 SCCA Vintage Race Car / Money Pit
1972 Mazda 808 ... 39k original Miles

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Ottawa510
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Re: SR20DET swap first start problems

Postby Ottawa510 » 24 May 2014 12:08

Hi Andrew, thanks for the tips. It wasn't much problem to remove the fan, and it turns out I don't need to remove the rad to try to turn it by hand. I mounted the longer studs and the new wheels, and pushed the car around. Maybe you have a moment to come by at some point. I could use your expertise.
Thanks

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Ottawa510
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Re: SR20DET swap first start problems

Postby Ottawa510 » 25 May 2014 11:31

Each time the starter clicks it turns the crank 2 - 3 degrees. I "started" the motor around 30 times, and the crank moved around 1/3 to 1/2 of a rotation. So the engine is not seized but very difficult to turn. I can't turn it by hand with a socket and wasn't successful with pushing the car around. Any other ideas? Thanks.

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okayfine
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Re: SR20DET swap first start problems

Postby okayfine » 25 May 2014 14:57

What sort of ratchet size/length were you using? I have a 1-1/16" wrench (~27mm) that's ~14" long and I can easily turn over an engine (SR or L) with it.

If you need to inspect, I'd pull the valve cover and oil pan and have a look to check the condition. Any history on the swap engine?
Because when you spend a silly amount of money on a silly, trivial thing that will help you not one jot, you are demonstrating that you have a soul and a heart and that you are the sort of person who has no time for Which? magazine. – Jeremy Clarkson

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JordanTr
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Re: SR20DET swap first start problems

Postby JordanTr » 25 May 2014 16:47

Sometimes the starter can be problematic. My friend's S14 SR had this issue since the auto starter it came with interfered with the flywheel making the engine seem seized. Switching to a manual starter solved his issue and the motor wasn't seized. :)

Long shot but worth a check maybe?
Jordan | '72 2 door KA project | '94 240sx RB26DETT | '97 Silvia RB25DET | '90 Audi 90 Quattro 20V (DD)

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icehouse
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Re: SR20DET swap first start problems

Postby icehouse » 25 May 2014 22:28

Sounds like you are turning the key to far. SLOWLY turn the key and see if there is a "sweet" spot.
I liked Hainz better...... Can we trade back?


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