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Discussion Starter · #1 ·
So as I've posted before, Im in Australia and 4bt's are not as common nor the bloody parts needed to repair.
Currently replacing the head as I had a suspected cracked head or gasket as cooling system was pressurizing and pushing coolant out. I've had advice that excessive coolant pressure could be related to higher than standard RPM, so any advice on that would be great. ;)
I will be installing a brand new head with ARP head studs and 60lb valve springs but questioning the block surface. Right now, time and $$ just aren't my friend with things in life at the moment so pulling the motor and decking it is not something that I can really manage.... I just need the car running.
Straight edge and feelers see some slight variances around and in between the cylinders. between 0.002 to 0.003 with 0.004 in between cyl 2 & 3 on intake side. Would this be within Cummins spec and ok to use? I have a genuine Cummins std thickness gasket here to use.

Im not fluent in engine rebuilding so go easy. Can spin spanners and RnR with manual guidance and specs but any advice is much appreciated.
Added pics below so feel free to point out any issues or concerns.
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Cylinder 1
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Cylinder 2
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So as I've posted before, Im in Australia and 4bt's are not as common nor the bloody parts needed to repair.
Currently replacing the head as I had a suspected cracked head or gasket as cooling system was pressurizing and pushing coolant out. I've had advice that excessive coolant pressure could be related to higher than standard RPM, so any advice on that would be great. ;)
I will be installing a brand new head with ARP head studs and 60lb valve springs but questioning the block surface. Right now, time and $$ just aren't my friend with things in life at the moment so pulling the motor and decking it is not something that I can really manage.... I just need the car running.
Straight edge and feelers see some slight variances around and in between the cylinders. between 0.002 to 0.003 with 0.004 in between cyl 2 & 3 on intake side. Would this be within Cummins spec and ok to use? I have a genuine Cummins std thickness gasket here to use.

Im not fluent in engine rebuilding so go easy. Can spin spanners and RnR with manual guidance and specs but any advice is much appreciated.
Added pics below so feel free to point out any issues or concerns.
View attachment 133338
View attachment 133339 View attachment 133340 View attachment 133341 View attachment 133342

Cylinder 1
View attachment 133349

Cylinder 2
View attachment 133350

Cylinder 3
View attachment 133351

Cylinder 4
View attachment 133352

Piston ID
View attachment 133353
See if this helps. NOTE, this is for the 6. They list 4 and 6 for the head but did not see any separate spec for the 4 for the block. Guess it would be a little less for the 4.
Cheers Steve
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As far as high rpm, id say that's not something id worry about. unless your talking around 4000 rpm. I've got a 4bt that regularly spins to 3500 rpm and ive been doing that for 100,000 kms.
So cummins states that the block needs to be .003 inches end to end max and .003 inches side to side.
The head states .003 inches side to side and .012 inches end to end.(another source said .008 for 4bt and .012 for 6bt)
So the next question is how much boost were you running and did you have head studs?
 

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The cylinders look very good. Something I see is playing tricks with my mind. In the photo of cylinder #2 it looks like there is step at the top of the cylinder, Is this just a photo illusion? Don't know of any reason higher RPM would build coolant pressure. That normally happens with a cracked head, bad head gasket, or cracked block. Do you have an engine serial number? Sort of curious how old you engine is. Greengoblin, why are you turning such high RPM? Are you using a special cam to change the power curve because on a normal 4bt you'd have virtually no torque at 3500 RPM. I assume you have a P pump because a VE doesn't like speeds over 3200. They make governor springs higher but the pump doesn't like it. Also, once you pass 2000 RPM the fuel economy starts dropping like you flushed a toilet.
 

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The cylinders look very good. Something I see is playing tricks with my mind. In the photo of cylinder #2 it looks like there is step at the top of the cylinder, Is this just a photo illusion? Don't know of any reason higher RPM would build coolant pressure. That normally happens with a cracked head, bad head gasket, or cracked block. Do you have an engine serial number? Sort of curious how old you engine is. Greengoblin, why are you turning such high RPM? Are you using a special cam to change the power curve because on a normal 4bt you'd have virtually no torque at 3500 RPM. I assume you have a P pump because a VE doesn't like speeds over 3200. They make governor springs higher but the pump doesn't like it. Also, once you pass 2000 RPM the fuel economy starts dropping like you flushed a toilet.
Looks like the head gasket is still on the block in some of those pic's, maybe what you are seeing as a step.
 

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Discussion Starter · #6 · (Edited)
As far as high rpm, id say that's not something id worry about. unless your talking around 4000 rpm. I've got a 4bt that regularly spins to 3500 rpm and ive been doing that for 100,000 kms.
So cummins states that the block needs to be .003 inches end to end max and .003 inches side to side.
The head states .003 inches side to side and .012 inches end to end.(another source said .008 for 4bt and .012 for 6bt)
So the next question is how much boost were you running and did you have head studs?
So to answer a few questions.... VE pump running 3200 gov spring, HX30w turbo.
Boost has been around 15-20psi before the turbo spat an oil seal but was set at 15psi by the rebuilder and has not been tinkered with since. It had head bolts which I believe would have been original OEM parts. Yes, I will be installing new head using ARP head studs ;)
 

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Discussion Starter · #7 ·
The cylinders look very good. Something I see is playing tricks with my mind. In the photo of cylinder #2 it looks like there is step at the top of the cylinder, Is this just a photo illusion? Don't know of any reason higher RPM would build coolant pressure. That normally happens with a cracked head, bad head gasket, or cracked block. Do you have an engine serial number? Sort of curious how old you engine is. Greengoblin, why are you turning such high RPM? Are you using a special cam to change the power curve because on a normal 4bt you'd have virtually no torque at 3500 RPM. I assume you have a P pump because a VE doesn't like speeds over 3200. They make governor springs higher but the pump doesn't like it. Also, once you pass 2000 RPM the fuel economy starts dropping like you flushed a toilet.
Hey Char,
Apologies for the pics of the cylinder bores..... all of those still have the old head gasket in place so yeah, what Blackduck said.... that lip would be the head gasket. Im happy to know the cylinders look in good condition. Is it worth me removing the small bit of scale at the top of the cylinder? Unsure on how to do without damaging the cylinder wall though.... or just leave it??
My current cooling system is a standard set up for my vehicle(Nissan GU Patrol) and never ran hot even when towing my 1.5t camper. Radiator is was brand new and runs into a pressure tank(brand new genuine.) that has a 'radiator cap'(new genuine also) that releases @ 14psi into an overflow bottle. Would the 4bt in good condition build excessively more than 14psi within the cooling system when hot? Is a 'bypass mod' something I should look at?
Engine had a damaged data plate on it when I bought it, but with yours and a few others assistance, were able to determine it was a Aug 1985 build out of the USA. ESN 44127375
I noticed you mentioning cams, and not really an issue on mine at the moment.... just a standard one. I do have concerns over its reliability though with me going to 60lb valve springs on the new head. I'd like to colt cam it somewhere in the future.

Side note, comparing old head Vs new one, I noticed the thermostat housing has a different diameter hole that goes from the back of the thermostat housing to the block. Old head is 12mm in diameter however the new on starts at 6mm(which you can see) but steps out to 9.5mm as it goes down to the block.
Do you know if one is better than the other?? Assuming the newer head has an upgraded design.
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If you're running an HX30W and have the boost limited to 15 PSI you've barely got it turned on. That may not even be 100 HP which it had originally. With that turbo you can safely run 30 PSI or a bit more. Of course to build that kind of boost you'll need to turn up the fuel a bit. 3200 RPM governor spring is fine. By adjusting fuel, pump timing, and turbo boost you can readily get to 200 HP. Don't need bigger injectors so long as the ones you have are in good condition. You really don't need a new cam as far as performance goes. Now, if you planned pushing power over 200 HP you might consider it but we have guys running 300 HP on the stock cam. I assume that photo of the thermostat area is the head. There have been some updates in those over the years. It is really strange that Cummins shows hardly any of the parts of your engine on the original build sheet. The 1st cylinder head which your engine would have had was 3913389. There have be 8 revised models since that. Don't know what the part number is on your new head but the newest number may be 3967444.
 

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Discussion Starter · #9 ·
If you're running an HX30W and have the boost limited to 15 PSI you've barely got it turned on. That may not even be 100 HP which it had originally. With that turbo you can safely run 30 PSI or a bit more. Of course to build that kind of boost you'll need to turn up the fuel a bit. 3200 RPM governor spring is fine. By adjusting fuel, pump timing, and turbo boost you can readily get to 200 HP. Don't need bigger injectors so long as the ones you have are in good condition. You really don't need a new cam as far as performance goes. Now, if you planned pushing power over 200 HP you might consider it but we have guys running 300 HP on the stock cam. I assume that photo of the thermostat area is the head. There have been some updates in those over the years. It is really strange that Cummins shows hardly any of the parts of your engine on the original build sheet. The 1st cylinder head which your engine would have had was 3913389. There have be 8 revised models since that. Don't know what the part number is on your new head but the newest number may be 3967444.
I think the fuel is up enough as I do soot a bit. Have had the injectors rebuilt to standard specs when the turbo was rebuilt so know all that is good. Hardest part around here is finding someone that knows the *bt engines/ve pumps and how to tune them for optimal performance including pump timing.
Head assembly Part No 3967432 was what was listed on the invoice. Part came out of DCEC China.

I will say, I did 'tidy' up and port the exhaust manifold while I had it off and also done the head as well to smooth things out. Didnt want to take too much out as Ive never ported anything before but thought.... while its all off, why not huh!

Ideally I want to hit that 200hp mark or slightly higher if its possible without compromising reliability.
Later upgrades I'd like to do are HX30w super and colt cam.... but thats a long way off right now.


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The 4bt with stock injectors and an HX30W can do about 225 HP. Gets a bit iffy trying to get much higher with a single turbo. Which size HX30W do you have? There were 4 sizes used on engines. All but one only came with a 6cm2 turbine housing. The inducer on the compressor side came in 40, 42. and 44mm for the regular versions and 46mm was the Super. The 40mm was mainly on industrial engines, the 42mm with the 6cm2 turbine came on road P pump engines and some industrial 4bt models, the 42mm with the 12cm2 turbine came on an industrial 6bt. That one does not work well on a 4bt. The 44mm is an import only item and has been used on engines built in China. It is still a genuine Holset unit. The 46mm Super never came on a Cummins but was used on a Deutz engine. The 44mm and 46mm Super are the most common ones we see used because they are more readily available and much cheaper. I looked up your head number 3967432 and Cummins shows that as a non sellable item. They have so many different part numbers for heads and I have no idea what differences there are. Does your new head have 9mm injector holes? All current heads are 7mm. The 9mm heads were known to crack more often. All early models were 9mm. If you are getting some black smoke, that means you have too much fuel or not enough air to burn what's there. Need to turn that smoke into power. Adjust your boost level up higher. You should see some smoke when you first take off due to lack of boost. When the boost kicks in the smoke should disappear. Boost is pretty much self limiting. It will only go higher if there is fuel to create the exhaust pressure. The cleaner you burn the fuel the cooler the engine temp will be. Diesels are the reverse of gas engines. A lean burn diesel runs cool while a lean gas engine is hot. On the injection pump timing, might PM member Eggman. Steve can tell you about setting the timing and what tools you will need to do it correctly. Have to be careful not to raise the timing too high or you take the chance of blowing the head gasket. The tools needed are not super expensive.
 

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Discussion Starter · #11 ·
The 4bt with stock injectors and an HX30W can do about 225 HP. Gets a bit iffy trying to get much higher with a single turbo. Which size HX30W do you have? There were 4 sizes used on engines. All but one only came with a 6cm2 turbine housing. The inducer on the compressor side came in 40, 42. and 44mm for the regular versions and 46mm was the Super. The 40mm was mainly on industrial engines, the 42mm with the 6cm2 turbine came on road P pump engines and some industrial 4bt models, the 42mm with the 12cm2 turbine came on an industrial 6bt. That one does not work well on a 4bt. The 44mm is an import only item and has been used on engines built in China. It is still a genuine Holset unit. The 46mm Super never came on a Cummins but was used on a Deutz engine. The 44mm and 46mm Super are the most common ones we see used because they are more readily available and much cheaper. I looked up your head number 3967432 and Cummins shows that as a non sellable item. They have so many different part numbers for heads and I have no idea what differences there are. Does your new head have 9mm injector holes? All current heads are 7mm. The 9mm heads were known to crack more often. All early models were 9mm. If you are getting some black smoke, that means you have too much fuel or not enough air to burn what's there. Need to turn that smoke into power. Adjust your boost level up higher. You should see some smoke when you first take off due to lack of boost. When the boost kicks in the smoke should disappear. Boost is pretty much self limiting. It will only go higher if there is fuel to create the exhaust pressure. The cleaner you burn the fuel the cooler the engine temp will be. Diesels are the reverse of gas engines. A lean burn diesel runs cool while a lean gas engine is hot. On the injection pump timing, might PM member Eggman. Steve can tell you about setting the timing and what tools you will need to do it correctly. Have to be careful not to raise the timing too high or you take the chance of blowing the head gasket. The tools needed are not super expensive.
Hey Char,
HX30w turbo has a 44mm compressor wheel, Im 99% sure this was purchased new and imported by the old owner or the business helping with his conversion. New head has 7mm injector holes.
Like I've mentioned before, Im pretty green to this technical stuff..... but I've bought the tools(dial gauge/magnetic base, telescopic bore gauge and micrometer) and spent the time to try and get this all measured up.... just hoping I'm doing it right. I've measured all piston protrusions and valve recession plus pistons bores.... (only thing that stands out to me is the exhaust side protrusion was a bit higher than the others) feel free to let me know if these are within spec. Im planning on using standard cummins head gasket.

Cyl 1 Protrusion: Intake side 0.0175 Exhaust side: 0.0190 Head Valve Recession: 0.047
Cyl 2 Protrusion: Intake side 0.0180 Exhaust side: 0.0255 Head Valve Recession: 0.047
Cyl 3 Protrusion: Intake side 0.0180 Exhaust side: 0.0205 Head Valve Recession: 0.047
Cyl 4 Protrusion: Intake side 0.0155 Exhaust side: 0.0195 Head Valve Recession: 0.047

Bore Measurements
Cylinder 1 Nth/Sth East/West
Top 4.0150 4.0165
Mid 4.0140 4.0165
Bottom 4.0145 4.0160

Cylinder 2 Nth/Sth East/West
Top 4.0160 4.0155
Mid 4.0145 4.0160
Bottom 4.0140 4.0165

Cylinder 3 Nth/Sth East/West
Top 4.0155 4.0165
Mid 4.0145 4.0160
Bottom 4.0140 4.0160

Cylinder 3 Nth/Sth East/West
Top 4.0160 4.0170
Mid 4.0145 4.0165
Bottom 4.0150 4.0165

This is how its looking now.
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You have a 7mm head but are your injectors also 7mm? All early injectors were 9mm but your engine could have had 7mm depending on when it was built. You're doing good work on the engine. Have you got your rocker arm stands machined for the studs yet?
 

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Discussion Starter · #13 ·
Char, old head had 9mm injector holes with 7mm injectors.... thank god because if it had of had 9mm injectors and with new head having 7mm holes.... prob would have heard me scream where you are half way around the other side of the world!!! Rocker pedestals all machined, cost me $45 ea.
Head studs/head all installed and now putting the bits and bobs back together. Taking my time a little and prepping, painting all the little things too like bolt heads etc. Actually baking the paint on in my 'oven' BBQ to cure it.
I had the exhaust manifold and turbo adapter ceramic coated so hoping that helps a little. Also got a new genuine water pump going on while Im at it.
Now I gotta drop the pan and check for water there and throw a new dipstick in the rear spot..... can't wait for that fun.
I'm also going to be in need of all 4 pump to injector lines and also the return manifold from the injectors...... any tips on best place to buy? Cummins Australia will need my left kidney to buy that.
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Discussion Starter · #14 ·
Righto, head is on but I think I may have some other dramas.:mad:
Head studs installed.... head installed to ARP torque specs with genuine standard gasket.
I did have a small issue where No2 2 Cyl exhaust push rod popped out of the rocker socket when adjusting valve clearances without me noticing and jammed up on the under side of the rocker arm and also side of the hole in the head that the push rod goes through. I didn't realize it was like that when manually cycling the crank and once I did notice, the push rod/rocker arm wouldn't move during manually trying to cycle the crank. I ended up needing to use a pry bar to lever the back of the rocker arm up to open the valve and pop the push rod back in its home socket in the rocker arm.

I am able to manually wind the motor over and seems tight under compression but no untoward noises..... Im not sure 'how' tight its meant to be. The issue I have now is that is seems to really struggle to crank under ign starting.

I'll explain the changes made whilst changing the head out and write off a few issues....

** Brand new DCEC head, genuine gasket and had rocker pedestals machined to allow ARP head studs on install. Also had PDD 60lb valve springs swapped in.
** Removed sump to install rear dipstick tube with no issues.
** Installed new oil drain tube to bottom of the block, again with no issues.
  1. Firstly started trying to crank with injectors, fuel lines all ready to go(less turbo and intercooler etc) but basically would not wind over by key.... as in it felt like not enough juice in the battery. Could still do manually but was tight.
  2. Added lithium jump pack and still did not crank as I think it should have.
  3. Rechecked valve clearances and all at spec at Intake = 0.010 and exhaust = 0.020
  4. Removed injectors to eliminate compression issue.... I don't know how to attach/upload the video I took of it, it will crank but seems to struggle and to me doesn't sound 'normal'. No nasty noises but not a flowing crank over. Seemed to draw a heap of power.
  5. During the above scenario, battery was fully charged and even put a lithium lump pack on during the video. Went from 14.8v with both battery & jump pack to 12.8v after trying to crank over for about 8-10sec without injectors in.(NB manual trans and was in neutral during all processes)
** Attempted removing pushrod cover on the side of the engine to inspect... but how the hell do you get that front bolt out from behind the IP??

Thinking Camshaft issue possibly, but other than that..... why would it not want to crank over normally with the changes I've done if I can turn over by hand??
Could something else have happened??
 
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