3500 swap questions

[Superdave]

Use your old sensors, the 3500 stuff dosen't work (or hasn't been tested yet)...

[PCGUY112887]

I know I should use the old sensors, but they are no where close to fitting in the places on the 3500. That is why I am asking, otherwise I would just swap them over. What sensors did you put in? Heck that one sensor on the left has a curved metal piece from the block, I haven't seen any sensor from either of these engines that could even consider fitting into it.

I just saw your sig Superdave, how in the world are you only making that much power? Not a very good tune yet?

[Superdave]

Lots more tuning to do... that was a baseline run.



that should help...

[IsaacHayes]

The temp sensor in the head should be a 1 wire (for gauges) and there should be a 2 wire in the LIM. Otherwise you should have a 3wire in the LIM... The 3500 has temp sensors in the head, try fitting either one of your stock sending units in the heads. IIRC it's a smaller hole and may only fit the sender for the gauge not for the PCM. You'll have to figure out something between your stock ones or a new 3 wire one.... And don't forget to plug the holes with something in the heads if you don't use those locations.

You should of cleaned the plenum before you ported it. You'll have a fun time getting all the shavings out with all the oil inside it. I know I did. I ended up putting it in a 5 gallon bucket with dish soap and blasting water and compressed air though the thing until it finally was all clean. If you have access to something better though that would be nice.

[PCGUY112887]

Thanks for the pic Superdave, I will double check fittings when I get home.

Isaac, my 3500 heads have a 2 wire sensor (which I assume is for temp) however I do not believe my LIM has any sensor in it (I will have to check when I get home). I thought a 3 wire just had to go into the head, and that ran the PCM, guage, and power.

I also don't know what you mean by oil. Why would there be oil in the plenum? The entire engine was clean when I pulled it apart, I did the porting and washed it a few times in water to get all of the aluminum out. It is still clean now.

[Superdave]

the 3 wire is larger and you'll have to drill/tap the head if you go that route...


I put a 2 wire in each head and it's working but if the front one ever goes bad then i'm hosed..

the 3 wire has a ground ref then an output to the gauge and one for the ECM.

[PCGUY112887]

Now ya see I am all cornfuzed. I could have swore that I remember reading that all "newer" 3x00 engines used 1 3 wire sensor that did the dash and the PCM. In the 3400swap guide, it says similar and suggests using the 3 wire sensor and mentions nothing of having to drill the head.

[Superdave]

Now ya see I am all cornfuzed. I could have swore that I remember reading that all "newer" 3x00 engines used 1 3 wire sensor that did the dash and the PCM. In the 3400swap guide, it says similar and suggests using the 3 wire sensor and mentions nothing of having to drill the head.

Right, because in a 3400 the 3 wire sensor fits into the LIM. the 3400 does not use a head temp sensor..

the 3500 does not have a sensor in the LIM and does use a head sensor, which is smaller than the 3 wire...


3 wire on the left, 3500's 2 wire on the right..

[PCGUY112887]

Can I just wire the PCM signal wire and the dash wire to the same signal wire the 2 sensor has? Or can it not work like that? (too much draw, etc).

[Superdave]

Can I just wire the PCM signal wire and the dash wire to the same signal wire the 2 sensor has? Or can it not work like that? (too much draw, etc).

Try it and find out


Not sure if it would work..

[IsaacHayes]

I would keep separate sensors for the gauges and the ECM. You will change the resistance/load/voltage by sharing one sensor and not get an accurate reading by either.

Well your plenum looks like it has oil in it from the pictures. My 3500 plenum had lots of oil in it too because of the PCV sucks it and it blows through everything. Stick your finger in there and feel around and on the top side too you might be surprised at the metal shavings you feel.... The 3400 manifold i ported was a lot easier to clean out since you blow water through the port and it's a straight shot out. The plenum is hard to get all the nooks inside.

[PCGUY112887]

I felt inside... it's not oil I think it may be stained from EGR gasses comming in since it really doesn't want to wash off either.

I did find a bit more metal though up on the lips, it's real clean now.

Thanks for the tip. It is drying now, I'll hit it with air tomorrow to ensure everything is OK.

[IsaacHayes]

Air won't budge it. For some reason that varnish (oil looking stuff) likes to hold the shavings/dust. When I said I used air, that was with a hose coming off an airgun while the thing was in the bucket of water with a ton of dish detergent. The air bubbled up and helped loosen all the shavings from the varnish. I have small hands so I can feel pretty deep in the manifold and I kept finding stuff several times when I thought I had it all. Brake cleaner was getting the varnish off but not all the shavings out. So I did the bucket and air trick. Hitting it with air alone won't blow anything out that didn't wash out already.

[PCGUY112887]

OK problem...

It no fit!





I have tried and tried, tons of lube, everything. Tried on both the 3100 crank pulley and the 3500 crank pulley, it won't go on either.

[bszopi]

Are you sure you are lining up the pin with the notch? I'm sure you are, but figured I'd mention it anyway.

One thing you might try... Heat up the pulley to allow the metal to expand and then try putting the new trigger on.