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RicardoJM
12-05-2010, 05:59 PM
I got an e-mail from a friend of a friend up in Conifer who has a 79 FJ40 that is used for plow duty; turns out the FJ40 is not running that well this winter and barely has enough power to make it up the drive. I had a chance to get up there this morning. The FJ40 was indeed idleing very poorly. We looked over the fuel system, idle speed and timing and did not see anything unusual. The vacuum hoses are old and should be replaced, but there were not any obvious vacuum leaks. An interesting note, this is the first time that I've come across an FJ40 with a flip up cover on the timing hole.

The next thing we were going to do was check the compression, upon removing the first spark plug it became clear why the rig was not running well. The engine was only running on two cylinders. Here is a photo of best plug in the rig.
http://www.risingsun4x4club.org/uploads/ricardojm/ray40/cyl3.jpg

Here is a photo of 6, 5, 4 and 1.
http://www.risingsun4x4club.org/uploads/ricardojm/ray40/pic1.jpg

This is cylinder 1
http://www.risingsun4x4club.org/uploads/ricardojm/ray40/cyl1.jpg

This is cylinder 2
http://www.risingsun4x4club.org/uploads/ricardojm/ray40/cyl2.jpg

This is cylinder 5
http://www.risingsun4x4club.org/uploads/ricardojm/ray40/cyl5.jpg

This is cylinder 6
http://www.risingsun4x4club.org/uploads/ricardojm/ray40/cyl6.jpg

In addition to the plug damage, the distributor cap was cracked. We replaced the plugs, cap and rotor and took the rig on a short drive - down the driveway and back - and it is running well again. This FJ40 is used to plow about 450 feet of driveway. I recommend to the owner that he prepare for getting a different engine and/or pulling the head off to determine what is going on as we don't know what caused the spark plug damage.

Short of pulling the head, how might we better determine what is going on with this engine?

TIMZTOY
12-05-2010, 07:47 PM
bore scope camara..

FYI i own this one.

60wag
12-06-2010, 05:50 AM
It sure looks like damage from something hitting the plugs but I'm wondering if its possible to get that from a lean running condition. Cyls 1 and 6 tend to be more lean than cyls 3 and 4 due to the length of the intake runners. Bad vac hoses, loose carb base or a bad intake seal could all cause a lean condition than made for some really high ignition temps. The plugs are black rather than white once they melted and became fouled, they probably went to a rich/non igniting condition.

rover67
12-06-2010, 07:09 AM
Whoa!

looks like it ate something!

Hey if it still runs, keep using it!

subzali
12-06-2010, 08:08 AM
Here's what eating something can do to sparkplugs...
http://www.risingsun4x4club.org/forum2/showthread.php?t=3102&highlight=head&page=2

But I also agree with 60wag that at least #1 looked like it melted, probably from some kind of lean condition...

Weird that new spark plugs solved it; I would have expected that whatever it ate would still be stuck in the head/valves.

nakman
12-06-2010, 08:21 AM
So did the thing eat some dirt or something, which got smashed between the piston and spark plug? Or Bruce are you saying the timing etc. got so far out of whack that the piston actually hit the plug?

Here's a theory: what if those were the wrong plugs, and they were sticking down too far? I know they say Denso.. but those crush washers don't even look like they've been crushed... as if someone knew they may smack the pistons so they didn't torque them down. :confused:


I'd run the thing- after it plows all winter, pull the plugs next spring and see what happened.

60wag
12-06-2010, 09:50 AM
Maybe they got so hot that something melted and cracked the insulators. The bits of ceramic and electrode fell into the cyl and were ajitated by the piston and peened anything in the cyl. I'm going with vac leak for the lean running condition.

RicardoJM
12-06-2010, 09:59 AM
So did the thing eat some dirt or something, which got smashed between the piston and spark plug?

Possible but not likely. Unlike many of the 40s in the club, the owner of this one doesn't open the hood very much:D. As I understand it, it got new plugs when he bought it in the late 90s and it gets some oil added every now and then. I looked down the carb to confirm it was running off the idle circuit and that the accelerator pump were working - everything looked pretty good. The air filter and housing are all very clean.

Here's a theory: what if those were the wrong plugs, and they were sticking down too far?

Interesting theory. I'll check the labeling on the plugs tonight to see what they say.

RicardoJM
12-06-2010, 10:01 AM
Maybe they got so hot that something melted and cracked the insulators. The bits of ceramic and electrode fell into the cyl and were ajitated by the piston and peened anything in the cyl. I'm going with vac leak for the lean running condition.

With the new plugs, cap and rotor the truck seems to idle well. The exhaust rusted and fell so it is loud. Would it take a large vacuum leak or would a small leak and lean running condition over a long period of time be able to cause this?

RicardoJM
12-06-2010, 10:34 AM
Interesting theory. I'll check the labeling on the plugs tonight to see what they say.

The plugs we pulled out were W14EX-U, which show for a 1981 2F and 3F (this web page) (http://www.globaldenso.com/en/products/aftermarket/plug/search/saudiarabia/automobile.html) in Saudia Arabia. It looks like, (this web page) (http://www.globaldenso.com/cgi-bin/global/plug/usa/4w/4w-plug.cgi?name=LAND+CRUISER&filename=4w-63.txt&action=search) that the plugs should be W14EXR-U in the USA.

What is the difference? Were they the wrong plugs?

The new plugs were Autolites from Checker/O'riely.

subzali
12-06-2010, 10:41 AM
The plugs we pulled out were W14EX-U, which show for a 1981 2F and 3F (this web page) (http://www.globaldenso.com/en/products/aftermarket/plug/search/saudiarabia/automobile.html) in Saudia Arabia. It looks like, (this web page) (http://www.globaldenso.com/cgi-bin/global/plug/usa/4w/4w-plug.cgi?name=LAND+CRUISER&filename=4w-63.txt&action=search) that the plugs should be W14EXR-U in the USA.

What is the difference? Were they the wrong plugs?

The new plugs were Autolites from Checker/O'riely.

I don't think that makes a difference. The number of threads is about the same as on my 2F so I don't think the plugs were sticking too far down into the combustion chamber.

Has he ever had the carburetor off for any reason?

SteveH
12-06-2010, 12:28 PM
The 'R' letter in the spark plug code is for 'resistor' plugs that provide noise suppression for the radio in the vehicle. I'm not sure if this affects the plug heat/operation in any other way - but generally, if a vehicle calls for resistor-type plugs, that's what you should use.

Air Randy
12-06-2010, 12:31 PM
Ricardo,

I don't think anything in the engine is hitting causing those issues. If it were that you would either still hear it or it would have punched a hole in the piston by now.

Running excessively lean can damage plugs but usually it takes a lot of miles for that to happen and this rig only gets used for plowing. On the other hand if the plugs havent been changed since the late 90's its possible.

It looks more likely to me that this could be caused by pre-ignition/detonation. He could have had a stuck advance mechanism on the distributor, or since this thing probably sits all year except for the winter it's probably full of crappy gas with water in it. Factor in that it sits for months and probably develops rust or corrosion on the electrodes. Then when you start it that crud can heat up and cause the air/fuel mix to detonate prematurely. Repeating that cycle will eventually weaken & melt the electrodes. Ask him if it ever "diesels" when he turns it off, that can be indicative of crud building up on the plugs. If he's using it for plowing he's also lugging it down a lot while pushing a big pile of snow, probably while he's flooring the gas. That can cause pinging that over an extended time could damage the plugs like this. The cracked distributor cap, if it was flashing around inside, could cause the plugs to fire at random times also causing damage.

Now that you've baselined the ignition setup, your best bet is to just do the compression check. If the numbers are good that tells you the valves and rings are good and no cracked pistons. If the numbers are low, squirt oil in the cylinders. If you don't see an improvement it's either a head gasket or bad valves. An improvement will tell you its probably rings.

Be sure and check for oil in the water and water in the oil too.

Air Randy
12-06-2010, 01:48 PM
More info on spark plugs:

Spark Plugs - Heat Ranges & Construction

A plug's heat range is its ability to transfer the excess heat from the insulator tip to the cylinder head. The speed of this transfer is commonly described by the term "hot plug" and "cold plug."

A "hot plug" means that the heat transfer is slow, causing the plug to operate at a higher temperature. A "cold plug" has a faster rate of heat transfer, thus it operates at a cooler temperature. In other words, a hot plug has a low heat range and a cold plug has a high heat range.

Plugs are available in different heat ranges to accommodate the operating conditions of different engines and driving conditions. A plug must operate hot enough to stay clean (i.e., not foul) and cold enough to prevent pre-ignition (premature ignition of the fuel-air mixture). If pre-ignition were not controlled, engine performance would drop and the plug would eventually destroy itself by overheating.The heat range is determined, for the most part, by the insulator material, the length of the insulator tip and the alloy material of the center electrode. The amount of heat transfer is affected by the size and shape of the space between the insulator and plug shell and by the quality of insulator material. A positive contact between the insulator and shell must be provided.

Here's what to keep in mind when selecting the right heat range for your car's spark plugs. A plug's heat range should be lower than the pre-ignition zone and higher than the cold fouling zone. In this lower temperature area, residues from fuel and oil additives are no longer burnt away and may cause the plug to misfire. Generally, a colder plug is better suited for high speed highway traveling. A hotter plug is better for prolonged idling and city travel.

Your friend should probably run a hotter plug for his application and consider changing them every 10 years or so :)

rover67
12-06-2010, 03:33 PM
pre-ignition spark plugs off the internets:

rover67
12-06-2010, 03:36 PM
some comparisons from the haynes manual:

Air Randy
12-06-2010, 04:20 PM
I'll bet none of the plugs in those pictures suffered pre-ignition for over 20+ years :D.

I agree some of them appear to have impact damage but if it was 1 cylinder I would buy it, but not virtually all of them. The plugs don't move so if they were hitting the pistons they would've been hitting them for over 20 years, but this problem appears to have occurred slowly over a period of time.

The only temporary thing I can think of that could have caused impact damage would be a large build up of carbon deposits that broke loose in the cylinder. This could have crushed the plug tips before breaking up enough to exit the the combustion chamber, but it doesn't explain the melted look of the electrodes.

If it was ingesting snow into the intake I suppose it could cause some damage since water doesn't compress.

SteveH
12-06-2010, 04:44 PM
I run hotter plugs in my plow truck for all those reasons. This '83 GMC (350 v8) would develop crud on the plugs that would short them out - even without an visible chunky deposits. When shorted, the truck wouldn't start. This would happen in as little as 10 hours of driving, using AC Delco OEM heat range plugs. The truck has HEI, too.

I went to NAPA and got the hottest plugs sold for a small block Chevy. No problems since then. Though I run a block heater, the truck is primarily driven hard in the winter, during storms, and essentially not at all in the summer. I also installed a 200 degree t-stat and plumbed the carburetor preheater hose valve to direct hot air to the air cleaner at all times. I want that sucker running hot every time it's driven, to drive off the diluted gas in the fuel, and to burn the plugs clean. So far, my strategy is working.
I installed a mechanical temperature gauge so I can see if I am overheating the engine, since the OEM gauge is junk.

Air Randy
12-06-2010, 07:28 PM
I run hotter plugs in my plow truck for all those reasons. This '83 GMC (350 v8) would develop crud on the plugs that would short them out - even without an visible chunky deposits. When shorted, the truck wouldn't start. This would happen in as little as 10 hours of driving, using AC Delco OEM heat range plugs. The truck has HEI, too.

I went to NAPA and got the hottest plugs sold for a small block Chevy. No problems since then. Though I run a block heater, the truck is primarily driven hard in the winter, during storms, and essentially not at all in the summer. I also installed a 200 degree t-stat and plumbed the carburetor preheater hose valve to direct hot air to the air cleaner at all times. I want that sucker running hot every time it's driven, to drive off the diluted gas in the fuel, and to burn the plugs clean. So far, my strategy is working.
I installed a mechanical temperature gauge so I can see if I am overheating the engine, since the OEM gauge is junk.

Yep, that makes sense. And that poor old 40 in the hills hadn't got fresh plugs in over 20 years, no wonder they were melted.

baileyfj40
12-06-2010, 07:41 PM
My .02 cents is pull a compression check cause it looks to me as if there is a broken piston ring that ate its way threw the piston land and broke the plug. Had that happen to me 77 about ten years ago.

RicardoJM
12-07-2010, 08:49 AM
Thanks for all the input. The dizzy cap was cracked at two of the screws, so it very well could have been vibrating and sending spark at the wrong time. The vacuum hoses are old and cracked and there very well could be vacuum leak(s).

Ray (the owner) has been following this thread and we have been e-mailing off line. Hey Ray; you can register on the forum and post up - it is a good bunch of people and they don't bite:D. Actually HeyRay would be a great forum name.

I really should have followed through with a compression test and vacuum check when we got it running again; it was on my list of objectives when I went out there:o. I suppose we can still get it done and post up the results when we have them.

Ray will check for vacuum leaks and be replacing the vacuum hoses.