explain this one? Bosch glow plugs.

bunja · 05-15-08, 11:56 AM

I was installing some glow plugs last night. The ones removed were the ND 067100-1680. I was replacing them with Bosch glow plugs. The Bosch were obtained through SOR and they were used

, since that is all that I could get within two days through SOR. I did order an all new set but I needed them ASAP so I thought I would have spare when the used ones went and the price was right.

Anyway, all the Bosch plugs showed a good glow when I tested them, and were free of any obvious defects and carbon build up. However, any of the four I got would fit in ports 3 and 4. None would fit in ports 1 or 2. I looked at the holes and did not see any obvious problems with carbon build up. The tips of the bosch are a little bigger in diameter than the ND.

So, has anybody else had problems with Bosch glow plugs. Why are the ports 3&4 bigger?

I ended up using two good plugs, and putting two of the toasted NDs back into port 1&2, just to keep me going for a while until the new plugs get in. She is running fine, for now.

lostmarbles · 05-15-08, 06:44 PM

Hi bunja

All I can think of is that there must be extra carbon build-up in combustion chambers 1 and 2 compared to 3 and 4. And that this is preventing the Bosch plugs from going in.

But as yet, I have never taken my head off so I don't know how likely this possibility is.

It is a bit of a worry that the plug dimensions between ND and Bosch are different for the same application. But I don't know how a very slight increase in the diameter of the heated part can have any negative effect (provided they can be fitted).

Perhaps you should try twiddling a drill-bit of the same diameter in the hole to clear any carbon build-up BEING VERY CAREFULL NOT TO DROP THE DRILL BIT INSIDE. (Perhaps wrap masking tape around the top of the drill bit to increase its diameter so it can't possibly fall in - and to give you something bigger to grip onto.)

Cheers
Tom

bunja · 05-15-08, 09:07 PM

Tom,
Thanks for the advice.
I can say that by eye (and not only mine) the Bosch plug is bigger by a mm or so. Another thing is that I also just had my injectors rebuilt and injector port 4 had far more carbon than the others and this had the best fit. I could not see any obvious biuldup in any of the glow plug holes. But, your advice seems sound for a guy with lost marbles. So I will try that next time I have a few minutes.

Thanks
Ben

amaurer · 05-15-08, 09:54 PM

wow, thats a weird problem you've got there. Where are they binding? do they sink in up to the threads and its just the threads that don't mesh? or do they hit something with the tip of the plug before then?

bunja · 05-15-08, 10:54 PM

The tip of the plug won't even go into the lower hole. I am using the Bosch in ports 3&4. It is the only way the cruiser will start.
All of the ND plugs go in without the slightest problem. I don't have calapers here but I will measure the plugs tomorrow.

1980 hj47 · 05-17-08, 03:00 PM

is it possible the threads on the bosch plugs go a bit deeper to get the plug to the right spot compared to the old densos? i had a similar prob and had to clean out the deeper threads in the engine to get NGKs in. but only in two seeminly random ports.... i thought the tips were not clearing at first.

bunja · 05-17-08, 06:12 PM

I followed Toms advice and it worked OK. The Bosch plugs on average were .03-0.05mm larger in diameter than the old ones. I know that it is a small difference but when it came down to it, it was a world of difference. Case closed

05-15-08, 11:56 AM	#1
bunja IH8MUD Junior Join Date: Oct 2006 Location: northern idaho Posts: 145	explain this one? Bosch glow plugs. I was installing some glow plugs last night. The ones removed were the ND 067100-1680. I was replacing them with Bosch glow plugs. The Bosch were obtained through SOR and they were used, since that is all that I could get within two days through SOR. I did order an all new set but I needed them ASAP so I thought I would have spare when the used ones went and the price was right. Anyway, all the Bosch plugs showed a good glow when I tested them, and were free of any obvious defects and carbon build up. However, any of the four I got would fit in ports 3 and 4. None would fit in ports 1 or 2. I looked at the holes and did not see any obvious problems with carbon build up. The tips of the bosch are a little bigger in diameter than the ND. So, has anybody else had problems with Bosch glow plugs. Why are the ports 3&4 bigger? I ended up using two good plugs, and putting two of the toasted NDs back into port 1&2, just to keep me going for a while until the new plugs get in. She is running fine, for now.

05-15-08, 06:44 PM	#2
lostmarbles IH8MUD Lifer Join Date: Sep 2007 Location: New Zealand (The other side of the world to most of ya!!!) Posts: 1,972	Hi bunja All I can think of is that there must be extra carbon build-up in combustion chambers 1 and 2 compared to 3 and 4. And that this is preventing the Bosch plugs from going in. But as yet, I have never taken my head off so I don't know how likely this possibility is. It is a bit of a worry that the plug dimensions between ND and Bosch are different for the same application. But I don't know how a very slight increase in the diameter of the heated part can have any negative effect (provided they can be fitted). Perhaps you should try twiddling a drill-bit of the same diameter in the hole to clear any carbon build-up BEING VERY CAREFULL NOT TO DROP THE DRILL BIT INSIDE. (Perhaps wrap masking tape around the top of the drill bit to increase its diameter so it can't possibly fall in - and to give you something bigger to grip onto.) Cheers Tom __________________ Name's really Tom & I have a 1979 BJ40 that is RHD and mainly "original" with Toyota PTO winch, 16" split rims, drums all round, B engine, H41 transmission and 12V electrics that I've owned since 1981 A hood is really a bonnet. A fender is really a guard. A windshield is really a windscreen. A zerk is really a nipple. A trunk is really a boot...........

05-15-08, 09:54 PM	#4
amaurer IH8MUD Lifer Join Date: Sep 2007 Location: Cupertino, CA Posts: 1,187	wow, thats a weird problem you've got there. Where are they binding? do they sink in up to the threads and its just the threads that don't mesh? or do they hit something with the tip of the plug before then? __________________ "... the motor car, after woman, is the most fragile and capricious thing on earth." - London Daily Mail 1908 1982 BJ42 "Krull"

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05-15-08, 09:07 PM	#3
bunja IH8MUD Junior Join Date: Oct 2006 Location: northern idaho Posts: 145	Tom, Thanks for the advice. I can say that by eye (and not only mine) the Bosch plug is bigger by a mm or so. Another thing is that I also just had my injectors rebuilt and injector port 4 had far more carbon than the others and this had the best fit. I could not see any obvious biuldup in any of the glow plug holes. But, your advice seems sound for a guy with lost marbles. So I will try that next time I have a few minutes. Thanks Ben

05-15-08, 10:54 PM	#5
bunja IH8MUD Junior Join Date: Oct 2006 Location: northern idaho Posts: 145	The tip of the plug won't even go into the lower hole. I am using the Bosch in ports 3&4. It is the only way the cruiser will start. All of the ND plugs go in without the slightest problem. I don't have calapers here but I will measure the plugs tomorrow.

05-17-08, 03:00 PM	#6
1980 hj47 IH8MUD Rookie Join Date: May 2007 Location: martinez, CA Posts: 8	is it possible the threads on the bosch plugs go a bit deeper to get the plug to the right spot compared to the old densos? i had a similar prob and had to clean out the deeper threads in the engine to get NGKs in. but only in two seeminly random ports.... i thought the tips were not clearing at first.

05-17-08, 06:12 PM	#7
bunja IH8MUD Junior Join Date: Oct 2006 Location: northern idaho Posts: 145	I followed Toms advice and it worked OK. The Bosch plugs on average were .03-0.05mm larger in diameter than the old ones. I know that it is a small difference but when it came down to it, it was a world of difference. Case closed