4d55 Might Max, Repair Questions, Usual Newbie Stuff

[cabbagehats]

Hey all,

New member, lurked a few times before. I don't actually own a MM but my friend is way into them and I am his go-to for repairs. He has a 1983 4d55-t mighty max 2wd that unfortunately developed a wicked oil leak en route somewhere and ran long enough to develop some rod knock. Found an '85 4wd 4d55 (56?)-t mechanics special on craigslist that had most of the rocker arms snapped and general rust and disrepair on the head from sitting for a long time. Story was that PO adjusted the valves too tight. Might have been a red flag there.

So, the plan. we are assuming for right now that the block on the '85 is fine and we are swapping the head from the '83 over and will work from there to get the engine running and then go over everything else. No idea what is going on with the injector pump so we will probably swap the '83 over as well. Pulled the head from the '83, it is perfectly flat, some cracks on the swirl cups but having trouble sourcing those. Both turbos are shot, leaking oil, and need repaired/replaced.

Here are my questions:

What places in the 4d55 can develop a leak that's fast enough to run dry on a 20 mile trip? My friend unfortunately put stop-leak in there before I got to look at it and we can't make it leak to diagnose. He said it was a heavy drip on the passenger side though. Engine runs fine but you can hear the knock in the higher rpms.

For temporary use only, and only if it won't hurt anything, can we block off turbo and run without until we get to repairs or replacement? Do they rebuild well or is a modern upgrade a better option?

Do the swirl cups in the head bust up and rattle in the combustion chambers? Are small cracks in them worrisome or just usual wear?

Thanks for any replies, These forums are amazing.

[frankwrench]

"What places in the 4d55 can develop a leak that's fast enough to run dry on a 20 mile trip?"

The first place I found, which still pisses me off now that I think about it, is at the back of the rocker cover towards the firewall. The rocker cover doesn't sit flush, BY DESIGN, on the block in the back. There's like a half-circle cut and every time that rocker cover comes off, you're gonna need more sealant back there (well, everywhere technically).

For me, when I first picked up my 4D55 that's where I was loosing some oil from old garbage sealant on the rocker arm cover, and the shape of the firewall and block resulted in passenger side oil drips.


Best I got to suggest. Good luck, we're all counting on you.

[skullzaflare]

So, broken rocker arms tend to be from broken timing belt or belt installed incorrectly. It is possible he over tightened the valves and they slapped the pistons breaking the rockers.

Passenger side oil can be leaking from Valve cover/turbo oil feed/turbo oil drain/oil filter/oil sensor/front seal/oil pump
on a d56 the vacuum pump is on the back of the alternator, which drains to the pain, that can leak as well. Most of these will not stop leaking with the stop leak.

Tell him STOP DRIVING IT, these cranks are very hard to source, that crank is probably already ruined now though

injection pumps should be the same, if you swap a pump you will need the dial indicator tool to set the timing
the injectors are probably going to be different between the years

Cracks on the head are common from poor maintenance, they can/will cause overheating as they will crack into the coolant chamber sooner or later, and start burning coolant

Turbos are only rated 50k miles on these engines, same rating as the timing belt. you will either have a no wastegate TC05-10a, or a wastegated TD04-9b (not the same as a 3000gt)

Replacement, the only GOOD place i have found is kinugawa turbos.


If you block the oil feed, and oil drain, you can remove the turbo and make a custom downpipe off the manifold. It will be gutless, but the non turbo version isnt much different
(likely will not be able to hit more than 45-50mph)

[cabbagehats]

So, broken rocker arms tend to be from broken timing belt or belt installed incorrectly. It is possible he over tightened the valves and they slapped the pistons breaking the rockers.

That makes more sense than overtightened. The fuel tank needs replaced because there's a huge dent on the front, looks like they drove over a stump. I think they just thrashed the thing with little maintenance.


Passenger side oil can be leaking from Valve cover/turbo oil feed/turbo oil drain/oil filter/oil sensor/front seal/oil pump
on a d56 the vacuum pump is on the back of the alternator, which drains to the pain, that can leak as well. Most of these will not stop leaking with the stop leak.

Vacuum pump is oil driven? Or cooled? Didn't check that, thanks. Would an oil cooler line bursting cause a sudden loss of oil?


Tell him STOP DRIVING IT, these cranks are very hard to source, that crank is probably already ruined now though

No worries, he ain't driving it. He parked it as soon as the oil light went on and got some oil, then he limped it home really slow and it's been parked since. But yeah the crank may be shot. His hope is to get the '85 running and then work on the '83 when he has time and rebuild the motor. donor motor might be a better option.


injection pumps should be the same, if you swap a pump you will need the dial indicator tool to set the timing
the injectors are probably going to be different between the years

So we are taking the head from the '83 and putting it on the '85 block. If we use the '83 injector pump as well then there shouldn't be any matching problems, right? And as far as the dial indicator, lining up the match marks aren't good enough in this application?


Cracks on the head are common from poor maintenance, they can/will cause overheating as they will crack into the coolant chamber sooner or later, and start burning coolant

To clarify, the '83 head is crack free. The brassy looking nozzle things where the injectors and the glow plugs go are what have cracks. Are these replaceable?


If you block the oil feed, and oil drain, you can remove the turbo and make a custom downpipe off the manifold. It will be gutless, but the non turbo version isnt much different
(likely will not be able to hit more than 45-50mph)

Excellent, that's what I needed to know. This is going to be VERY temporary. My friend wants to daily this thing so guts are a must. Does the injection pump need to be adjusted for lack of turbo?

Thanks for your insight!

[cabbagehats]

"What places in the 4d55 can develop a leak that's fast enough to run dry on a 20 mile trip?"

The first place I found, which still pisses me off now that I think about it, is at the back of the rocker cover towards the firewall. The rocker cover doesn't sit flush, BY DESIGN, on the block in the back. There's like a half-circle cut and every time that rocker cover comes off, you're gonna need more sealant back there (well, everywhere technically).

For me, when I first picked up my 4D55 that's where I was loosing some oil from old garbage sealant on the rocker arm cover, and the shape of the firewall and block resulted in passenger side oil drips.

Yeah, I'm actually a Toyota guy and the 20r and the 22r have the same half moon plugs for the valve cover, except they have them on both the front and the back. I got that leak well on the radar :)


Best I got to suggest. Good luck, we're all counting on you.

Thanks, man. The pressures on!

[skullzaflare]

That makes more sense than overtightened. The fuel tank needs replaced because there's a huge dent on the front, looks like they drove over a stump. I think they just thrashed the thing with little maintenance.



Vacuum pump is oil driven? Or cooled? Didn't check that, thanks. Would an oil cooler line bursting cause a sudden loss of oil?



No worries, he ain't driving it. He parked it as soon as the oil light went on and got some oil, then he limped it home really slow and it's been parked since. But yeah the crank may be shot. His hope is to get the '85 running and then work on the '83 when he has time and rebuild the motor. donor motor might be a better option.



So we are taking the head from the '83 and putting it on the '85 block. If we use the '83 injector pump as well then there shouldn't be any matching problems, right? And as far as the dial indicator, lining up the match marks aren't good enough in this application?



To clarify, the '83 head is crack free. The brassy looking nozzle things where the injectors and the glow plugs go are what have cracks. Are these replaceable?



Excellent, that's what I needed to know. This is going to be VERY temporary. My friend wants to daily this thing so guts are a must. Does the injection pump need to be adjusted for lack of turbo?

Thanks for your insight!

The vacuum pump on the d56 is oil lubed, I do not know how/where the pump is on the d55. I know the ranger d55 had a normal ford pump up top.

If an oil cooler line broke, you would drain the pain in less than 30 seconds ( i have done it before lol)

The injection pump isnt bolted to the head. If you remove the pump, you have to put the pump back in time. The timing markers of course you need to follow for the pulleys to be lined up, but the pump has timing, similar to a distributor, except more dangerous and no light lol.
I would suggest not touching the pumps, swap the head, adjust valves, use as is

the cracked pieces i would need a picture of, i cant picture the parts you are talking about, unless you mean the injectors themselves or the return plumbing

[MainstreaM]

4D55 has the vacuum pump on the alternator as well. The D56 alternator/pump is a slight upgrade for the 55.

[Uncle Spence]

Turbos are only rated 50k miles on these engines, same rating as the timing belt. you will either have a no wastegate TC05-10a, or a wastegated TD04-9b (not the same as a 3000gt)


Turbos are only good for 50,000 miles? Then what? Are you just supposed to rebuild them ever 50k? I wasn't aware of that figure.

[skullzaflare]

Turbos are only good for 50,000 miles? Then what? Are you just supposed to rebuild them ever 50k? I wasn't aware of that figure.
Thats what the manual stated lol. Said it should be rebuilt around 50k lol. Guess depends how hard you are on it lol

[cabbagehats]

​Might have been the oil cooler line then, I didn't get a real good explanation of what happened. Just he was driving it, the light went on, he went and got oil and limped it home. could be the stop leak fixed the line. But not likely.

Thanks for the heads up on the pump, We didn't get to it yet so we'll take your advice and try leaving as is first. Nice thing about this progressing so slow is there's plenty of time to dodge mistakes.

here's the pictures (I hope):

first two show the worst of the cracks, first picture is #1 and the second is #4. Last one is #1 again and you and your viewers might care to notice I got the intake and exhaust valves all switched up. :clap:
185251852618527

[cabbagehats]

4D55 has the vacuum pump on the alternator as well. The D56 alternator/pump is a slight upgrade for the 55.

Nice. Will check that out. The two motors look pretty identical. Any idea where the d56 gets its extra .2 liters?

[Clouse]

Nice. Will check that out. The two motors look pretty identical. Any idea where the d56 gets its extra .2 liters?
The 4d56 has a longer stroke. I would assume you could purchase a 4d56 crank and turn a 4d55 into a d56.

I bought a 4d56 from a shop in Canada and have been really happy with it. Very little difference between it and my old 4d55 physically. It's a hair more powerful, and also gets a hair worse gas mileage...

[cabbagehats]

The 4d56 has a longer stroke. I would assume you could purchase a 4d56 crank and turn a 4d55 into a d56.

I bought a 4d56 from a shop in Canada and have been really happy with it. Very little difference between it and my old 4d55 physically. It's a hair more powerful, and also gets a hair worse gas mileage...

Aha, thanks!

Hmm, more power, less mileage. Always a compromise. Are the heads on the d56 still aluminum? Love Port Angeles by the way, beautiful!

[cabbagehats]

Skullzaflare, can you weight in on those pictures? I swear, I usually don't mix up valves! That was a first!

[skullzaflare]

Yes the heads are still aluminum.

I have never seen a crack right there, so i cant weigh in on if its safe to run or not

[cabbagehats]

Yes the heads are still aluminum.

I have never seen a crack right there, so i cant weigh in on if its safe to run or not

Ah shoot, I gotta grab the manual then so I can find out if they are replaceable or what their proper name is. Thanks anyways!