99' Base 5 speed Cranks / No start / No codes / New CPS

[Chi-Town]

It's unlikely to lose compression in all 6 cylinders at the same time but I'll check just to be sure.

I'll report back after the pump experiment

[Chi-Town]

Well we got a winner, 50 psi compression

I guess I'll start prepping the spare 2.7 to swap in

Thanks guys!

[Fiddlebog]

Originally Posted by Chi-Town

Well we got a winner, 50 psi compression

I guess I'll start prepping the spare 2.7 to swap in

Thanks guys!

That doesn't mean the engine is bad. Try tossing a little oil in the cylinders that are getting bad compression. That will help if you are getting bad sealing.
Otherwise, there's probably something wrong with the valves.

[Chi-Town]

I stuck my bore scope in after the compression test, you can see valve collision marks on the crown of the piston. I'm pretty sure the chains are broke or worse.

I bought a running car for parts so I have a spare 2.7.

I just resealed the cam covers and installed plugs and tubes.
I'll do the IMS and RMS next week when it cools down here.

[blue62]

Originally Posted by Chi-Town

Well we got a winner, 50 psi compression

I guess I'll start prepping the spare 2.7 to swap in

Thanks guys!

I don't know the spec for these engines. I do seem to remember reading something about them running low tension rings or something of that nature. So perhaps the rings are not sealing well.
50 psi doesn't sound good if that is average for all cylinders my guess would be it skipped timing or worse. You could confirm that by pulling those plastic plugs and checking cam timing.

[Chi-Town]

Yeah 140~psi is spec from what I've read.

It's not worth me dealing with as I have a good lower mileage 2.7 sitting here and the time to invest swapping it.

[Fiddlebog]

Originally Posted by Chi-Town

Yeah 140~psi is spec from what I've read.

It's not worth me dealing with as I have a good lower mileage 2.7 sitting here and the time to invest swapping it.

Well if it's a timing problem (which it seems it is based off of your observations), you're gonna need to get that motor out of there anyways. Sounds like it's gonna need a rebuild.

[Chi-Town]

Pulled the motor and found the LH manifold and cat full of milkshake.

Appears to be either a cracked head or D chunk cylinder.

I've got the 2.7 back in the car already should have it running this week.

[blue62]

Sounds like your decision to swap out motors was the right one.
Hope all goes good with the swap out and shake down.

[78F350]

In reply, I don't think the 2.5 runners will seal on the 2.7L heads. I've got all the parts (2.7L head and both types of intake runner) and I can get a look at the exact measurements tonight.

With mine, I was going the other way and put a 2.7L intake on a 2.5L engine. That had plenty of surface for mating the seal. The gasket of the 2.5L runner looks like it will fall inside the 2.7L intake though:


I see two fairly simple ways to modify.

• Make a rigid plastic or metal adapter plate to fit the 2.5L intake passages and give them a surface to seal onto.
• Use the 2.5L cable throttle on the 2.7L intake. 'Adapt as needed' to fit. Block off the resonance cross-tube. Mid range airflow will not be optimal, but it's a compromise already, running on the 5.4 DME (ECU).

Here's an ugly adaptation making a 2.7L throttle work on a 2.5L engine. Tubing clamped onto tubing to make it fit. Not my work or preference, but it did run pretty well. You would want to go the other way 2.5L throttle onto 2.7L intake.



Much more complicated and has a few details I'm sure I haven't considered:
Run the 2.7L engine how it was made to be run. Swap in the DME/immobilizer box/key fob, gas pedal, and adapted wire harness from the parts car. Keep the 2.7L engine intact as stock.