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3800 Series 2 Engine Swap



Starting this upcoming weekend, I will be doing an engine swap on my mother in law's '99 Grand Prix (3800 series 2 normally aspirated). Apparently, it fell victim to the stupid plastic plenum design, which leaked coolant into the engine. I have almost everything in place:

Remanufactured 3800 series 2 long block engine (from Jasper)
Aftermarket upper intake manifold / plenum with a metal sleeve for EGR hole
Exhaust manifold, intake manifold, valve cover, thermostat, and water pump gaskets
New plugs and wires
Fuel injector o-rings
New accessory belts

I read through the Chilton service manual, and they mentioned that I need a special tool for the fuel line quick disconnect. I found the tool at a local parts store.

Is there any other special tools that I need? Do I need a special tool to remove or install the crankshaft balancer? They indicate a special tool to remove it, but I am wondering if I can use a standard gear puller without damaging the rubber insulation. Also, can I hold the flywheel by using a large screwdriver or prybar, so I can loosen the crankshaft balancer bolt. I swapped the engine in my old Prelude several years ago and I did not need any special tools to remove the balancer or hold the flywheel.

Is there anything special about the crank position sensor that I need to watch out for? I know not to pry on it. Are there any adjustments that I need to do when transferring it over?

Do I have to separate the exhaust manifold from the catalytic converter or can I just unbolt the manifold from the block?


Just an update:

We got the old engine out. It took a 13-hour day to do it. What a pain in the butt. It took almost 4 hours to figure out how to get the last bolt that connects the tranny to the engine block. It's located on the back side of the block and you can't even see it. We had to remove the rear exhaust manifold and tilt the engine forward to get to it. There is a lot of bracing in the rear of the block that makes it difficult too.

This engine also has a crap load of sensors all over it. There are many that are hard to see and so you have to be careful to unplug them all before lifting the engine out.

This past weekend, we got all of the parts off the old block and started transferring them over to the new engine. In the process, we f***ed up the flywheel, trying to break loose the crankshaft balancer bolt loose. That bolt was on there really freaking tight. If we had the proper flywheel lock tool, it would not have been a problem, but we shoved a bolt into one of the flywheel holes to keep it from turning. It turns out that the flywheel is actually really weak for this car, which surprises me. We ended up ovaling the hole out and bent the flywheel slightly. The good thing is it only costs $35 at GMPartsdirect.com, which also surprised me it was that cheap.

There are 2 black plastic elbow pieces (for coolant) that run into the belt tensioner assembly bracket. Both of these elbow pieces broke when trying to remove them. It looked like they were glued in place but I don't think they were. I think the Dexcool crudded up the o-rings and basically epoxied itself. Everything that had to do with the cooling system was stuck (thermostat, elbow pieces, sensors, etc.). This really makes me frown towards the Dexcool product.

The last hurdle is a 0.25 inch dowell pin for the crankshaft position sensor. We cannot get the old dowell pin out of the old block. The new block does not have the dowell pin (or it has been pushed into the block or broken off). This kind of blows because it is the last hurdle to overcome.

The plan for this upcoming Saturday (3/2) is to finish transferring the components over and hopefully we can install the new engine on Sunday.


it fell victim to the stupid plastic plenum design, which leaked coolant into the engine this is what the DeXKILL does, it kills anything plastic over time , First day I bought my car (warranty was up) I removed the DexKill and put the green stuff


All of the parts have been transferred over to the new engine. I had to make my own dowell pin for the crank position sensor. I ended up buying a 1/4 inch metal rod from a hardware store and cut it to length and it fit perfectly.

To prime the oil system, I went to Home Depot and bought a $10 sprayer (for insects or weeds) and a barbed fitting. The sprayer is the type that you have to pump the handle up to pressurize it. I connected the brass barbed fitting to where the oil pressure sensor goes and put oil in the sprayer. I flowed about 2 quarts of oil into the system. I don't know how effective it is, but I guess we shall see.

We dropped the engine into the car and have started hooking everything up. Once again, the rear transmission brace was a pain in the butt, along with the exhaust manifold. Since we are working on this on Saturdays only, it is taking a while to do. Next weekend (3/10), everything should be ready and hopefully the engine will start without any leaks.



The last day went as planned, for the most part. The engine fired up easily and there were no exhaust or fluid leaks. It ran smooth and quiet. The only deal was the "service engine soon" light turned on. Apparently, it was already on before the engine swap, according to my mother-in-law. So I went to Auto Zone and had them scan it. The error code was DTC P0341, which is a camshaft position sensor range / performance problem. We bought a new sensor and installed it and had the code cleared. I drove it home and it did not trip a code. But when I fired it up a second time, the "service engine soon" light came on again. I had it scanned again, and it turned out to be the same error. I don't know what the deal is. I cleared the error and we will have to wait and see if it returns (I am suspecting that it will).

But for the most part, everything went smooth and now my mother-in-law can enjoy a nice running car again. I plan to change the oil at 500 miles, before giving her the keys. I didn't go with the Dexcool this time. I used regular green glycol from Prestone.

Hopefully, this will be the last time working on this car.


I finally figured out what caused the camshaft position sensor error. Apparently, we routed the wiring harness wrong and the A/C compressor pinched the harness against the engine block. The camshaft signal wire was pinched so much that the sheath was partially rubbed away, causing it to short against the engine block, instead of sending a signal to the ICM and PCM. After routing the wiring harness correctly and taping over the exposed wire, and then clearing the SES code, the car ran great. The SES light didn't come on after that.

It's been a long frustating week of troubleshooting. The multimeter was quite useful in pinpointing the problem.

Victory is had, finally.


I know this is not the 3800 series 2 but I have a 1992 Pontiac Bonneville that has a 3800 series 1 tuned port injection engine. There has been no flaws with this engine though it does have a column shifter so it had a shifter linkage sticking my dad found out and it was not letting the neutral safety switch realize we are in park. We adjusted the linkage and the car has started every time since. My ses light used to come on at 2000 rpm and turned off at 3000 rpm. Then it stopped after a while. I do not know whether it is a short or something really happened. It still runs and drives fine when the ses light comes on, but it just comes on. I've been wondering if I could swap a 3800 series 2 for a 3800 series 1. I am planning to get another car with a 3800 series 1 or 2 but from what i've read the injection system of a 3800 series 1 and 2 are different. So from what i've read I like the 3800 series 1's injection system better.


Staff member
You would need the complete engine wire harness and ecu form the donor car.