Best Inline-6 ever made?

[AutoMechanic]

They have really sensitive cooling systems. Everything needs to be replaced. All heater and radiator hoses, water pump, thermostat, fan clutch (getting a good one can be tough), make sure it has the fan shroud for the mechanical fan, make sure the electric fan is coming on at the right time (or at all), and that the radiator is in good shape. A lot of times the radiator gets plugged up and can’t cool effectively. They’re also prone to air bubbles. All of this has to work together, if one thing is slightly off they’ll run hot.

The cooling system was designed for a tiny 2.5L 4 cylinder. Then Jeep/AMC decided to toss in a bigger 6 cylinder without upgrading the cooling system.

Replace every part especially after sitting any real period of time. I’d make sure all this is up to par before replacing the engine.

I appreciate the info. I wasn’t aware it was one of those systems that you had to replace everything. Since we bought it in 2005 between 2005 and 2014 it went through 6 radiators so that explains that. Still has original thermostat and hoses too. It has the fan shroud still if I remember correctly.

 

[jeepman3071]

Agreed. I can’t find anyone else who knew that 2000 and especially 2001 were bad for those. Our 2001 has been sitting since 2014 after we replaced the head and head gasket and it still wasn’t fixed so something is wrong somewhere no mechanic could figure it out either it over heats after cutting off so when we get some more money we are going to get a new engine.

It's usually a sequence of events that takes out the cylinder head and often the engine in the 2000-2001 4.0L engines.

1. The coolant isn't changed at proper intervals (these came with green coolant originally, so every 3 years)
2. The iron block/head will rust, plugging up the cooling passages
3. The engine over heats, or is run for prolonged periods above normal operating temp, cracking the head
4. The coolant mixes with the oil, and often goes unnoticed for a period of time by the owner, as the coolant bottle occasionally empties
5. By the time the cracked head is noticed, the engine is consuming a lot of coolant, which has been mixing with the oil
6. The cam bearings are smoked by now, and the oil pressure goes to zero at hot idle (stop lights) which is usually when people finally notice there is an issue.

By then it is too late, new engine time. This head casting is weaker than prior castings, so it is more susceptible to cracking. The head might even crack with no prior overheating, but that is much more rare.

 

[AutoMechanic]

It's usually a sequence of events that takes out the cylinder head and often the engine in the 2000-2001 4.0L engines.

1. The coolant isn't changed at proper intervals (these came with green coolant originally, so every 3 years)
2. The iron block/head will rust, plugging up the cooling passages
3. The engine over heats, or is run for prolonged periods above normal operating temp, cracking the head
4. The coolant mixes with the oil, and often goes unnoticed for a period of time by the owner, as the coolant bottle occasionally empties
5. By the time the cracked head is noticed, the engine is consuming a lot of coolant, which has been mixing with the oil
6. The cam bearings are smoked by now, and the oil pressure goes to zero at hot idle (stop lights) which is usually when people finally notice there is an issue.

By then it is too late, new engine time. This head casting is weaker than prior castings, so it is more susceptible to cracking. The head might even crack with no prior overheating, but that is much more rare.

Yes every time it over heated we put a new radiator in it because that’s what my dads mechanic said to do. He ran it overheated several times he is the type he isn’t stopping unless the thing shuts off on its own. When we reassembled everything it didn’t appear that the head was sitting evenly on the block it looked like the block may have warped. And the coolant was only changed when the radiator was replaced no other times.

 

[jeepman3071]

Will disagree with that. The N52 is a tank of a motor, very stout. Also makes significantly more power, and thanks to valvetronic, is significantly cleaner and better FE. Everything a motor is supposed to do, it does it better. Plus, I hate working on those old MXX motors. LOL

I agree with this, I like driving the M54 engines, but they are more fragile than the N52 it seems. If overheated, they will pull the head bolt threads from the block, and only a time-sert in the block can fix it. This is commonly diagnosed as a bad head gasket, and mechanics will replace numerous head gaskets and even cylinder heads wondering why it won't fix the problem. The M52TU/M54 also have a few more plastic cooling system components (plastic water pump for one) that can crack/break and cause issues. The N52 has an expensive electric water pump that usually fails between 80-120k miles, but the rest of the cooling system is a bit tougher.

While the N54 isn't considered to be a reliable engine, it is certainly durable for the tuning potential it has.

 

[jeepman3071]

Yes every time it over heated we put a new radiator in it because that’s what my dads mechanic said to do. He ran it overheated several times he is the type he isn’t stopping unless the thing shuts off on its own. When we reassembled everything it didn’t appear that the head was sitting evenly on the block it looked like the block may have warped.

Yep, over heating is usually what kills them. The cooling system is very marginal in XJ Cherokees. In my own 2000 XJ I had a 3 row radiator which kept it cool, the stock one was useless. A friend's sister got a Jeep 4.0L so hot that it actually seized up back in high school. That was a 90's Jeep, so we just threw another head and gasket on it (old one warped) and it ran for another 25k-30k miles before it was sold. It did burn a lot of oil after that though.

 

[AutoMechanic]

Yep, over heating is usually what kills them. The cooling system is very marginal in XJ Cherokees. In my own 2000 XJ I had a 3 row radiator which kept it cool, the stock one was useless. A friend's sister got a Jeep 4.0L so hot that it actually seized up back in high school. That was a 90's Jeep, so we just threw another head and gasket on it (old one warped) and it ran for another 25k-30k miles before it was sold. It did burn a lot of oil after that though.

Dang. Never knew they were notorious for this. I appreciate your information. I guess it’s new engine time then. It’s my understanding only a 2000 or 2001 engine will work in the 2001 correct?

 

[walterjay]

Ford 200 cubic inch six is among my favorites, and far from a "Wrong Answer". It's simple, light and enjoyable in an old Mustang.

I had that engine in my first car a 64-1/2 Mustang. It was reliable and carefree.

 

[jeepman3071]

Dang. Never knew they were notorious for this. I appreciate your information. I guess it’s new engine time then. It’s my understanding only a 2000 or 2001 engine will work in the 2001 correct?

Any block from a 1991-2001 Cherokee, 1991-1999 Wrangler, or 1993-1998 Grand Cherokee will work. The head does need to be of the later style 2000-2006 style. For some of the new Jeeps that had the coil rail ignition with the similar head, the blocks were different.

If it were me, I'd get a good engine block from the above mentioned year range of vehicles, then buy a new cylinder head from Clearwater cylinder. You can find them on ebay they have the improved version of the cylinder head that won't crack. Put the new head on the good used block and you are good to go and have a basically bullet proof engine.

 

[AutoMechanic]

Any block from a 1991-2001 Cherokee, 1991-1999 Wrangler, or 1993-1998 Grand Cherokee will work. The head does need to be of the later style 2000-2006 style. For some of the new Jeeps that had the coil rail ignition with the similar head, the blocks were different.

If it were me, I'd get a good engine block from the above mentioned year range of vehicles, then buy a new cylinder head from Clearwater cylinder. You can find them on ebay they have the improved version of the cylinder head that won't crack. Put the new head on the good used block and you are good to go and have a basically bullet proof engine.

Thanks. Yes the new head we put on originally is a Clearwater one it still has that one on there only has one startup on it to see if that was the issue.

 

[Nick1994]

Thanks. Yes the new head we put on originally is a Clearwater one it still has that one on there only has one startup on it to see if that was the issue.

Go spin the fan clutch and see if it free wheels. Mine was so bad at one point when my grandpa owned it that you’d shut off the engine and the fan clutch would spin endlessly (pointless).

 

[AutoMechanic]

Go spin the fan clutch and see if it free wheels. Mine was so bad at one point when my grandpa owned it that you’d shut off the engine and the fan clutch would spin endlessly (pointless).

Thanks I’ll give that a try to see hopefully it won’t be locked up or anything.

 

[jeepman3071]

Go spin the fan clutch and see if it free wheels. Mine was so bad at one point when my grandpa owned it that you’d shut off the engine and the fan clutch would spin endlessly (pointless).

Yep, if putting in a new engine I'd do the following:

-3 row radiator (csf is usually what I use)
-New hoses
-New fan clutch
-195* stant superstat
-Hesco high flow thermostat housing
-New Mopar or GMB water pump (stay away from the Flowkooler garbage)

Flush the system a few times before replacing the above, make sure your A/C condenser fins are clean, and you will run at the proper temp even on a hot day. When my XJ had the above setup I could tow my trailer on a 100* day and still stay in the 200-210* range.

 

[Nick1994]

Yep, if putting in a new engine I'd do the following:

-3 row radiator (csf is usually what I use)
-New hoses
-New fan clutch
-195* stant superstat
-Hesco high flow thermostat housing
-New Mopar or GMB water pump (stay away from the Flowkooler garbage)

Flush the system a few times before replacing the above, make sure your A/C condenser fins are clean, and you will run at the proper temp even on a hot day. When my XJ had the above setup I could tow my trailer on a 100* day and still stay in the 200-210* range.

I put in a FlowKooler in mine last summer

 

[blingo]

No Steyr Monoblock Diesel has ever suffered head gasket problems.
And now for some Best_Inline-7 thread ever made.

 

[Trav]

If I had to choose just one it would be the Opel CIH engines especially the C36GET L6. Worth reading..

Lotus Carlton - Wikipedia

en.wikipedia.org

Opel cam-in-head engine - Wikipedia

en.wikipedia.org

 

[BISCUT]

Magnesium. And thank god, those iron blocks are heavy as ****. The N52 is a much better engine. Probably the best engine BMW has made, if you rank reliability highly.

You are certainly correct. I forgot it was Magnesiun not Al. I had a N52 in my 2008 E90. Great motor even with the weeps. I got rid of mine due to the transmission just not being comfortable to drive. Wish it was a stick! I'd probably still have it.

 

[jeepman3071]

I put in a FlowKooler in mine last summer

Yeah I'd go back to a stock one if your Jeep is running hot. I put 2 Flowkooler pumps in Jeep 4.0s, and ended up taking them out shortly after. One made a clanking noise (WJ 4.0L) and it turned out the plate riveted to the impeller had come loose (common problem), and the other one was in an XJ 4.0L and it still ran hot when at speed. An old engine builder from the Jeepstrokers.com forum told me they caused "too much" flow for the radiator and to try a stock one. I didn't really believe him, but a stock GMB pump with 3 row radiator cured that Jeep completely.

 

[Flyingdutchman]

Mine does not have 3 stage manifold, but mid range is really, really good for such engine.
Of course, 3 stage intake is in works

Yes i compared the maximum torque of the non disa e36 2.5 i6 against the n52 2.5 i6 with disa and if i am not mistaken the n52s maximum torque was already around 2500 3000 rpm and the non disa engine was around 4500 rpm.

I agree with this, I like driving the M54 engines, but they are more fragile than the N52 it seems. If overheated, they will pull the head bolt threads from the block, and only a time-sert in the block can fix it. This is commonly diagnosed as a bad head gasket, and mechanics will replace numerous head gaskets and even cylinder heads wondering why it won't fix the problem. The M52TU/M54 also have a few more plastic cooling system components (plastic water pump for one) that can crack/break and cause issues. The N52 has an expensive electric water pump that usually fails between 80-120k miles, but the rest of the cooling system is a bit tougher.

While the N54 isn't considered to be a reliable engine, it is certainly durable for the tuning potential it has.

My electric waterpump is the original one and is now at 224k miles, i think i will change it before it fails after 15 year. But yes its expensive.
I had the radiator fail at 190k, the plastic side cover that is clamped to the alluminium leaked inbetween.
The o ring in the plastic pipe mounted on the front of the cylinder head becomes hard and also seeped a little. I have replaced this at 210k.


Due to the variable heat management the ECU will give warning when its over 120 celcius, this is way too hot. The reason why its so high is that the engine is allowed to run at 110 celcius due to ECO mode when the ECU notices youre cruising at low load at a constant speed. Due to the length of the ALU cylhead its more sensitive to deforming.

When people do not stop immediatly when they get a warning they will ruin the engine. There is no time to drive to the next exit.
I would open the bonnet and put the car on accesory mode, then the electric fan should keep turning due to to high engine temp.

QUOTE mightymousetech: Will disagree with that. The N52 is a tank of a motor, very stout. Also makes significantly more power, and thanks to valvetronic, is significantly cleaner and better FE. Everything a motor is supposed to do, it does it better. Plus, I hate working on those old MXX motors. LOL

Yes i agree, when you compare the N52 to its competitors at that time it had the highest ouput per liter for an n/a 6 cyl engine.
Too bad they couldnt/didnt make them after that, would love to see 100hp per liter n/a inline 6es.

 

[Snagglefoot]

The Chevy 292. Half the farm trucks in America had them. LOL.

 

[A_Harman]

Wut … my grandma had this

View attachment 35257

Beautiful. The Chrysler Leaning Tower of Power.