Topic: 2.5l engine interchangability...

[tawd77]

Hi, Im new here and was referred by a guy over at Jeepz.com - He said if anyone could answer my question it would be you guys... so here I go -

My jeep is an 89 wrangler with a 2.5l TBI that is shot. I have located a good 2.5l out of a 2000 model jeep. Are there any differences between an 89 longblock and the 2000 longblock? I was hoping to be able to swap all the stuff off my engine onto the newer one and be done... Will it work? Thanks for the help!!

[jcsanders79]

I know that when my TJ 2.5 was rebuilt the shop sent a YJ block to be bored and rebuilt while they pulled mine.  Put all of my TJ stuff on it.  Don't know the exact years but they can be interchangable.

[tawd77]

Yeah, I think its gonna work too.. I just have to remember to put on an 1989 water pump as the newer one is reverse rotation. Im going to start the swap tonight... I hope it works!!

[chardrc]

i believe the blocks are basically the same. you just need all the electronic, intake manifold, and the accessories from the tbi 2.5.. i think jeffy knows some differences but i don't think they are too important.

[tawd77]

I got the junk motor pulled out last night... I will start swapping the parts off that motor onto the 2000 motor tomorrow.. Hope everything fits!!

[stan98tj]

i think the heads are different. i bought a new head for my 98 before i realized i needed a whole new long block the head they sent me was from a YJ 2.5 and it was a hair different and there was also a dummy hole that needed to be plugged that isnt on the newer 2.5s...u should look into this as im not sure if it makes all that much of a difference

[tawd77]

The head seems to be the same externally so far. I havent made much progress but I switched the harmonic balancer/crank pully, alt. brackets.. Which the brackets dont fit right because the timing chain covers are a little different. I should have switch the TC covers but was too lazy. So I just made the brackets work. swapped distributors, exhaust man./intake man., oil pressure sensor... still need to swap flywheels/clutch assemblies, and get the new water pump and thermostat put on. Then it will be ready to go back in. Hopefully I will get all that done tomorrow later today!

[tawd77]

Ok, Got a problem... actually 2 problems...

1. The original engine had a hole in the cylinder head where the Temp sensor screwed in. The new head does not have this hole. So, I have nowhere to hook up the temp. sensor. The jeep idled at 2k RPM even when warm so I grounded out the temp sensor and started the engine again and the idle went down. Maybe it was a coincidence, but im pretty sure the computer uses the temp sensor to control the idle speed. Anyone have any ideas where I can mount the temp sensor?

2. The engine is not cooling. The newer motor had serp. belt, so the water pump was reverse rotation. I put in a standard rotation pump, and a new thermostat and either the pump isnt working, or the thermostat isnt opening. I think it st he pump, because the bypass hose that runs from the thermostat housing to the intake manifold isnt even getting hot and it doesnt rely on the thermostat... Anyone have any ideas why this is happening?

Besides that it seems to run quite well.

[Mr_Random]

If the intake heater hose isn't getting hot I'd suspect it to be the pump.

As for the sensor, I'd try to tap and thread a hole in the coolant outlet on the rear of the intake manny, it's near enough to the stock location anyways.

[Mr_Random]

Since I can't edit:

Did you notice a good little boost in power, other than it running well? The CR on the new engine should be 9.2:1, whereas your old one had 9.1:1. I'm not sure about the 2.5 from 2000, but the 4.0 of the time lost some power due to smaller exhaust valves/outlets (can't remember which one of the two), so that may negate the small increase in power...

Yeah, good luck on fixing your little problems!

[tawd77]

I didnt notice a boost of power because I bought it broken so I never tried the last motor, and I still havent taken it out of the garage. Want to get this stuff fixed first.

I could probably just put a "T" in the heater hose that goes from the thermostat housing to the intake. Screw the sensor into the "T" and it should get a good reading since it bypasses the thermostat. What do you think?

Im still working on the no coolant flow issue... I will mess with it more later today.

[Mr_Random]

WOW, someone else on at this time! haha

Okay, I guess that makes sense...

As long as it's a very short T, that will put the sensor in the flow of the coolant, then it should work, otherwise it'll be too far away and not get an accurate reading.