
120Y difficult to start from cold.
- Datto_610
- Datsun God
- Posts: 2976
- Joined: Sun Jul 20, 2008 10:39 am
- aka: Greg
- Location: Christchurch, NZ
- Location: Christchurch, NZ
- Contact:
120Y difficult to start from cold.
I changed the oil and filters on the Y after work on friday. Also did the spark plugs. The ones that I pulled out are Denso w16ep-u and the ones I replaced them with are NGK bp5es. The Denso's I took out had the grey brown colour on the end so were working fine. But ever since replacing all these things its been a lot harder to start from cold. Will turn over but doesn't want to fire for a while but once its running all seems to be fine and starts first time after being warmed up. Earlier today though I started her up before going out but was only running on 3 cylinders so popped the bonnet and found that #1(closest to the firewall) wasn't firing. Took the spark plug out and it was oil fouled so took out #2 and that one was carbon fouled
Haven't checked the other two yet.I swapped them over after cleaning the oil off and she started on all 4 again. Am I right to assume that the w16ep-u plugs are 'hotter' which is they weren't oil/carbon fouled??? Also she's very smokey on start up definitely needs valve stem seals done. This is my daily at the moment so would like to make it more reliable.

- classicdat
- Committee Members
- Posts: 3260
- Joined: Wed Apr 21, 2010 9:59 pm
- aka: Vaughan
- Location: Datsun Central, Christchurch
- Contact:
Re: 120Y difficult to start from cold.
Greg do you have the old plugs to bang back in, see if that fixes it
at least you will know where you are at. I think, but could be wrong, 5s are hotter than 6s in the NGK range so really they should be spot on. What oil did you use, do you know if it is the same as the car was running? Is the choke still operating OK, just a thought that it may have been altered during your work. You have been using the choke haven't you Greg? 


Datsuns from A to Zed
- Datto_610
- Datsun God
- Posts: 2976
- Joined: Sun Jul 20, 2008 10:39 am
- aka: Greg
- Location: Christchurch, NZ
- Location: Christchurch, NZ
- Contact:
Re: 120Y difficult to start from cold.
Haha of course I've been using the choke! Still have old plugs will bang em back in this arvo and report back. Have no idea on what oil was in there but replaced it with Penrite 20w60. Was still a bit hard to start from cold before I changed everything, would have to hold foot on the gas even with choke out before it idled on its own. Now it idles on its own once it eventually starts.
- classicdat
- Committee Members
- Posts: 3260
- Joined: Wed Apr 21, 2010 9:59 pm
- aka: Vaughan
- Location: Datsun Central, Christchurch
- Contact:
Re: 120Y difficult to start from cold.
When were the points looked at last? They have the most impact on starting. They need serviced every 5-10K
Datsuns from A to Zed
- Datto_610
- Datsun God
- Posts: 2976
- Joined: Sun Jul 20, 2008 10:39 am
- aka: Greg
- Location: Christchurch, NZ
- Location: Christchurch, NZ
- Contact:
Re: 120Y difficult to start from cold.
I wouldn't know when they have been looked at last. Probably a good idea to sort those out, points are unfamiliar territory for me. Do I buy new ones or can I adjust the current ones?
- classicdat
- Committee Members
- Posts: 3260
- Joined: Wed Apr 21, 2010 9:59 pm
- aka: Vaughan
- Location: Datsun Central, Christchurch
- Contact:
Re: 120Y difficult to start from cold.
You could do either, depends on condition, most people tend to biff them, they are not expensive. You need to set them right, and really need a dwell meter to be accurate. Cleanliness is next to Godliness on this one too. Ensure you clean the preservative off the face of them and grease the cam.
I'll be free after Show weekend if you can wait and I'll give you a little tutorial.
Adam put up a link for Tony's ute, but not on the build thread, from super cheap, could be worth searching their site and giving it a go.
Remember to set the timing once you have finished.
I'll be free after Show weekend if you can wait and I'll give you a little tutorial.
Adam put up a link for Tony's ute, but not on the build thread, from super cheap, could be worth searching their site and giving it a go.
Remember to set the timing once you have finished.
Datsuns from A to Zed
- Datto_610
- Datsun God
- Posts: 2976
- Joined: Sun Jul 20, 2008 10:39 am
- aka: Greg
- Location: Christchurch, NZ
- Location: Christchurch, NZ
- Contact:
Re: 120Y difficult to start from cold.
Thanks Vaughan, I'll be away show weekend but might get it sorted pretty soon. Taking Lizzie for her first lesson on thursday 

Re: 120Y difficult to start from cold.
A bit late but could be useful for someone.
I was running the same NGK plugs in my old mazda ute (which burned some oil) and it would always foul the plugs so I swapped for the Champion equivalent (N11YC I think) and didn't have any more problems.
Comparing the two, the Champion looks like it sticks further into the combustion chamber.
I was running the same NGK plugs in my old mazda ute (which burned some oil) and it would always foul the plugs so I swapped for the Champion equivalent (N11YC I think) and didn't have any more problems.
Comparing the two, the Champion looks like it sticks further into the combustion chamber.
- classicdat
- Committee Members
- Posts: 3260
- Joined: Wed Apr 21, 2010 9:59 pm
- aka: Vaughan
- Location: Datsun Central, Christchurch
- Contact:
Re: 120Y difficult to start from cold.
Probably not the make that made the difference, it will be the heat range, a champion 11 is a hot plug (Higher the number = hotter), matches an NGK 5 (Lower the number = hotter for NGK) heat range from memory. The problem with a hotter plug is it can cause detonation in a high compression enginekicker wrote:A bit late but could be useful for someone.
I was running the same NGK plugs in my old mazda ute (which burned some oil) and it would always foul the plugs so I swapped for the Champion equivalent (N11YC I think) and didn't have any more problems.
Comparing the two, the Champion looks like it sticks further into the combustion chamber.

Datsuns from A to Zed