Precombustion chamber temperature???

[Pony]

There is a large back story to this tractor in regards to what I've replaced, etc, but I'll try and keep this a little shorter otherwise my post will run for pages.
1960 Massey Ferguson 35 tractor with the 3A.152 Perkins 3 cylinder diesel, obviously this is the indirect injection version, also naturally aspirated.
Was purchased new by my grandfather and pretty much used and abused since then, no idea on the hours, except to say LOTS.
This engine has removable precombustion chamber covers on the side of the head, one for each cylinder, on the same side there are two exhaust ports. The exhaust ports exit between cyl #1 &2 and then again behind #3.
I've got what I believe to be a localised overheating issue caused by corrosion in the block leading to a coolant flow issue.
The temperature gauge sender is at the thermostat housing off to the front of #1 cyl. Gauge won't read due to not getting hot enough.
Infrared thermometer shows about 50c, therefore thermostat won't open, it is currently removed to allow coolant flow through radiator.

5 minutes at 1200 rpm from cold will show temps on the precombustion chamber covers of #1 45C #2 75C #3 95C.
With thermostat removed coolant is flowing, with thermostat installed it's not opening and obviously bypassing.
So my question is,
Is the precombustion cover temp giving me a indication of cylinder temps or head coolant temps or a combination of both?
I'm confused by the large variations in temps, there's not much free space to measure directly off the head, but in front of #1 is pretty much same as precomp temp whereas between #2 & #3 is in the 80C if run for longer.
I measured under a load and got approx #1 55C #2 120C #3 140C.
As stated I'm leaning towards blaming coolant flow through block for getting the rear two cylinders hot, but I've got a nagging little voice saying maybe I'm measuring combustion temps and it's a fuel issue.
Head is new, waterpump is new, injectors rebuilt and pop-off pressure set, radiator is clean, hoses new, thermostat when installed was new and verified opening on stovetop. New fuel lift pump, filters, injector pump timing checked (was correct), #2 compression 360psi, other two 380-390ish. Good oil pressure
I keep blowing head gaskets, on #3, where my heat appears to be. I haven't simply shotgunned the new parts, every time I done a head gasket I found what I thought was the problem and fixed it, and while each of those was definitely buggered, it appears that heat is the underlying issue.
Just trying to figure out why.
There is more, but as I said, trying to keep this a little bit shorter than war and peace.
Thanks

 

[Truck Shop]

Is it blowing the head gasket in the same spot each time?

 

[Delmer]

How corroded were the head and block when you did the head gasket? Easy to see an abused tractor running on hard water and plugging up with scale, but you'd also see that pretty well if you had the head off.

 

[56wrench]

You could pop out the core plugs on the side of the block and check for scale buildup. Then flush water down through and see what, if anything, comes out. I heard of a dead mouse once in an engine block causing an overheating issue

 

[Pony]

Is it blowing the head gasket in the same spot each time?

Yeah pretty much.
First two photos are last replacement, appears #2 is gone as well as #3.
3rd photo was a previous time where only #3 has gone.
I initially thought block deck mightn't be flat, but I can't get a 3 thou feeler gauge under a straight edge in the location it's blowing, or anywhere else for that matter.
Copper head gasket, workshop manual calls for a coating of sealing compound, I have been using CopperCoat.
Specs for torque is 60lb, shop I've been buying parts from said they use 70lb and don't coat gasket.
It is currently back together at 70lb and dry gasket.
Liners are polished, should probably rebuild bottom end, but oil pressure is good and compression acceptable.

 

[Pony]

How corroded were the head and block when you did the head gasket? Easy to see an abused tractor running on hard water and plugging up with scale, but you'd also see that pretty well if you had the head off.

This was the original head.
You can also see the water galleries in the photos I posted above.
The coolant drain tap in the block was clogged up and needed a bit of compressed air persuasion to get it to flow. Decent amount of fine sediment removed this way.
Also flushed radiator/block, entire system til water running clean.
On the last head gasket replacement I also got a bit caveman and got a long nose compressed air nozzle and spent about an hour blowing chunks out of the block through the water galleries. Mostly large sand size particles, but also some up to nearly fingernail size.
So yes definitely internal corrosion of block, as above probably should be totally stripped and block acid bathed, but as stated I'm a little concerned that the temps I'm seeing on the precombustion chamber covers aren't due to coolant flow restriction.
This tractor does have sentimental value and I will use it, but it's to small to "really" use and it's just about got to its time and money limit.
I've found a product called Evaporust which isn't supposed to harm copper/brass etc, but still dissolve rust.
I've had it in the cooling system for two days now so we'll see if that makes a difference.
I've also had a copper washer soaking for the same time to monitor for corrosion and it is good so far, so this stuff might actually work.

 

[Pony]

You could pop out the core plugs on the side of the block and check for scale buildup. Then flush water down through and see what, if anything, comes out. I heard of a dead mouse once in an engine block causing an overheating issue

Yeah I thought of that but I think I'd need to remove a fair bit of stuff, eg injector pump to be able to reinstall them.
As above I blew the galleries "clean" and then flushed with water once head was back on.
With the thermostat removed you can see the waterflow returning to the radiator aggessively, so obviously there is a flow path.
My suspicion was that there is a massive restriction between #1 & #2, which is why #1 is running so cold and #3 so hot.

#3 cylinder is definitely getting hot, you can see in the photo how it blued the precombustion chamber cover. This occurred on a previous head gasket replacement, on that occasion I put it down to bad injectors, upon testing they were gushing like a garden hose and pop off pressure was at 180 atmospheres, spec is 120.
That was fuel coming out of front exhaust port. I think grandad got his monies worth out of those injectors.
Also was running thermostat in that photo with the blued precomp cover.
Was also running under heavy load, although not for long.

 

[Pony]

As an aside, in the last photo above with the blued precomp cover.
The elbow housing you can see coming off below #1 precomp cover is actually the coolant feed into the block.
The waterpump is divorced, the thermostat housing is just out of frame off the front of the head.
So in my restricted block theory, this would allow coolant to enter at #1 and exit at #1 without getting back to #2 & #3.
But as stated I'm just not sure what temperature I'm actually measuring on the precomp covers.
Cylinder temps or coolant temps or a combination?

 

[Truck Shop]

Evaporust does work, if kept totally submerged for 48 hrs and that depends on how thick
the scale is. A rough idle temp for average diesel at idle on exhaust ports is 275 to 325F.
That's a across the board temp for most engines without any load. For a 14L on road
application once coming to a stand still and idled for three minutes a pyro will normally
settle out at 300*F--that's average.

 

[Pony]

From memory, in current state, temp on external of exhaust manifold nearest #3 is about 10-20C above #3 precomp.
I don't think I've ever compared the front exhaust port to the front two precomp temps.
I'll go do that now and report back.
It's not so much the actual temps I'm seeing on the precomps that are concerning me, it's the massive difference between them.
With the fact #3 is the hottest and that's where I'm blowing the head gasket, something is obviously not happy.
Well you've all seen the photos, a lot of things obviously weren't happy, but as I fixed one thing, it exposed the next weakest, and so on.
But I think we're at a point where there isn't too much more left.

 

[Truck Shop]

Does this engine smoke at idle--unburnt fuel smell?

 

[Pony]

Does this engine smoke at idle--unburnt fuel smell?

Yes, big puff at start up and light haze at idle, I was putting that down to thermostat removed and front cylinder not getting up to temp?
Run inside shop with doors/ windows open, makes your eyes water after a while.

 

[Pony]

Engine was run a couple of ago to circulate evaporust.

Ambient temp 30C-86F
Before starting
Precomp all 36-97
Head all 38-100
Exhaust all 38-100

3 minutes 800rpm
Precomp #1 50-122
Precomp #2 65-149
Precomp #3 80-176
Exhaust manifold front 74-165
Exhaust manifold rear 85-185

10 minutes 1200rpm
Driven down hill and again up hill
Precomp #1 51-124
Precomp #2 115-239
Precomp #3 143-289
Exhaust manifold front 127-260
Exhaust manifold rear 148-298
Head front 46-115
Head between #2/#3 Precomp 80-196
Thermostat housing 52-125
Btm radiator hose 40-104

No thermostat fitted.

 

[Truck Shop]

I would say 2 & 3 close to normal 1 isn't firing--jmo.

 

[Pony]

Funny you say that, I had the same thoughts heading down the shed.
Injector lines aren't real easy to get to with fuel tank on, but was able to crack #3 and #1 lines at rear of injector pump and did get a miss introduced.
However did get the feeling that there was a "bigger" miss when #3 open than #1.
Don't know if that is even possible or if I was imagining things.
I installed new injector nozzles and had them spray pattern tested and pop off pressures set. When i removed them last, for head gasket replacement there was a light coating of carbon on all of them.
If compression is sufficent, how can it not be going bang?
Not doubting you, i genuinely don't know, how else can i confirm this apart from the what ive done cracking the line?
Just got a call, I have to go up to my properties and sort some bulls out, so won't be able to do any immediate troubleshooting.
But please keep the ideas coming I'll be in and out of service and respond when I can.
Thanks for everyone's input.

 

[Pony]

I would love to do a leak down compression test but don't have the gauges and a set costs more than the tractor is worth.
Could #1 have bad rings or similar and still show good compression?

 

[Truck Shop]

At three minutes in at 800 rpm your temp is off by 50* from 1 to 3--that isn't a cooling issue, imo.
Recheck your valve adjustments.
It could have low compression on 1-just enough to cause a lazy cylinder, maybe a broke ring
anything is possible setting where I am.

 

[Pony]

Yeah I can appreciate the difficulties troubleshooting from half a world away. Thanks again for your time.
The last compression test I did was a couple of head gaskets ago, as stated #2 was lowest at 360, the other two were higher, BUT that was two head gaskets ago.
I can do another test when I get back to see if anything has changed. Can also check valves then.
Just in case, be advised I am using aftermaket parts, Sparex, Bepco, etc, so it certainly is possible that a new part I've fitted isn't good. I definitely fall into the trap of thinking that I've replaced it, therefore it's got to be good.
Rightoh, big drive time.
Thanks

 

[Mobiltech]

Fuel delivery rate from number 1 on the injection pump may be low.

 

[tctractors]

That engine has the Thermo-start heater plug in the inlet manifold, they do fail allowing raw fuel into the cylinders, number 3 would get a good thump of it, take the valve out and reconnect to the fuel pipe then start up the engine and see if it leaks put the wire on as well, on the block being full of crap just knock out the core plugs they are only low cost and easy to tackle, the engine has to have a regulator in the cooling system to work correctly, we used to put Wellseal on the head joint its brown gravy looking stuff, I think it might be called Permatex possibly in other locations, the engine parts are for buttons in the U.K. with engine rebuild kits to be found from many suppliers, the heads, blocks and cranks are also for just a few coins brand new, its possibly the most common engine ever built and with the highest reputation.