Ferguson FE35 Glow Plugs

Ideas please. I have a 1957 FE35, 4 cylinder diesel, UK built (where I live). In 1997, shortly after getting it, I had an exchange cylinder head fitted, with a glow plug for each cylinder. This transformed it's starting ability. This modification was a factory option for cold weather areas but not for the UK. Those glow plugs lasted until early this year, when I had starting difficulties and on investigation found 3 glow plugs were not glowing. 4 months later, the starting difficulties have returned and on testing, the glow plugs are not glowing.

While it is simple enough to replace them, any advice on what to look for, to see why they have failed so soon would be appreciated. I do about 50 hours a year, light work on my small holding and 5-8 vintage ploughing matches each year.

If they all 4 failed at once, there is a fuse in there someplace. Or another wiring problem behind the dash more than likely.
I bought 4 brand new ones for my 23C while i was still putting it together- they did no good. Starting fluid is needed every time, and you can't heat glow plugs at the same time- so a waste of nearly $300.
But if yours starts with em, and none heat up, hopefully you just have a wiring problem.

You could change "brands" of glow plugs.. there is a difference. you'll have to do the research tho, length, thread pitch ect.
SOME are rated at 8v while others are rated at 12v.. so keep THAT in mind if your running straight off the battery.
Does the system have a timer? or are you holding them on?? Whats the count if your holding them?
8-10 seconds is about right. anything longer than that & your cooking the plugs..?? You'll have to check the engine manual to be certain of the time..
I worked on a system in a sail boat once where the manual said to hold for 90 seconds.!!!!
I went thru the entire fuel system w/ the same no start condition until I found that "tidbit" of information in the operators manual..

The 35's have a heating coil under the dash, visible thru a hole in the dash, and if it isn't a whole 90 seconds to heat to bright orange, it sure feels like it when you are sitting there with your fingers going numb..

Which glow plugs do you use? If they are the factory type glow plugs they were wired in series so if one goes out they all go out. If they are the factory type plugs they won't last long if wired in parallel, they are only rated for about 2 volts hense the need for the coil under the dash.

Here is some information that I found from JDEM,

"The glow plugs differ between early and later engines.

Early engines have glow plugs with a thread size that is M14 X 1.25 mm. That is what the 829162M1 has for threads. It is a plug rated for no more then 2 volts. This is not a common thread size for glow plugs.

Later engines use glow plugs with a thread size that is M10 X 1 mm. This IS common and the same as many GM 6.2 and 6.5 diesels use.

If you want to change, first you have to know what you've got. I had a Allis Chalmer ED40 with the same Standard 23C diesel engine and the original glow plugs were awful and expensive.

If you have the M14 threads, here are a few alternatives from other brands.

Delphi HDS317 is the same as the MF 829162M1 and is only rated a max of 2 volts. Must be wired in series.

A Delphi HDS806 is an 11 volt plug with the same M14 threads, but protrude into the engine a bit further by 1/8"

An NGK Y-402-2 has the same M14 threads and is rated at 8 volts. It is only 1/16" longer and may be fine.

The later 23C engines with the M10 threaded glow plugs are wired in parallel instead of series and run on 10-12 volts.

I don't have my ED40 Allis Chalmers anymore. I made adapters and put in glow plugs with different threads for better starting with cheaper plugs. But that was 25 years ago and there's more stuff available now. I used Delco plugs for GM diesels, but they have changed too. The glow plugs made and sold by Delco are useless. However the Delco AC60G plugs are excellent and are almost burn-out proof. That because Delco doesn't make them. They are German Beru plugs stuck into Delco boxes."

I changed my sytem over to parallel set-up. Got them from UK
https://www.rimmerbros.co.uk/Item--i-LL1530BM

Work fine, when it's cold (for North Carolina) I count to 30 on heat and it starts every time. FWIW I also changed the starter to Lucas M50 which spins the engine over faster.

Thank you for your comments. Today, the replacement glow plugs arrived and I have fitted them. The tractor started very easily. I think that I
had been over cooking the plugs, i.e. Having them on heat for two long. Originally I was advised to give 3 X 10 seconds bursts of heat, with 5
seconds between each, wait another 5 secs then turn the key further to engage the starter. I am not sure who made the original glow plugs, the
replacements were NGK 4602 Y-909R, which my local motor factor identified as being the same plug.

I have refitted the same and will use less heat. I had ordered the new plugs before receiving the suggestion about a different brand. Here, in
the UK it is cheaper to order the plugs, mail order, than to buy them from a motor factor, who had to order them from their main regional depot,
rather than having them in stock.

The plugs are in parallel. It is a modification, rather than an original fitting and not wired in series, as per the original cold climate equipment
(pages G 33 - G 35 of my service manual, pub no 819 147 M1

Once again, many thanks for your comments. I am a regular reader but infrequent contributor