Just wondering if anyone on here knows if I can swap a 1999 SOHC from an S Series into a 1997. If it can be done, what if anything needs to be modified?

 

@jamnar , can you help on this one?

 

What trans is in the 97?
was the 97 a DOHC or SOHC?

Have you checked compression on the 99 motor, wet and dry to make sure it is healthy enough to make this worthwhile?
How many miles on the 99 engine?

 

The engine is a brand new 1999 Saturn crate motor that I bought for my 2002 S Series after being given false info from a dealership that the part number i gave them for the engine was correct for my car. It is not. Heads are different as well as exhaust.
I have it up for sale and someone asked me if it would work in their 1997. Im trying to get the money i paid for it back.
let me check with the guy who messaged me as to the model as well as the transmission. I will let you know as soon as I get a response, if I get one.
I really appreciate all of the help you guys can offer. I really need to get this gone and recoup my losses

 

First, a picture of the crate engine would be helpful in identifying what you got and what it could be used in.
Whether you have a 1999 (which most were 2nd gen) or a 2002 engine (which is 3rd gen) there are four possibilities:
1. SOHC Federal emissions.
2. DOHC Federal emissions.
3. SOHC California emissions.
4. DOHC California emissions.
Does the engine include the intake or exhaust manifolds?
SOHC and DOHC exhaust manifolds are different and have different bolt patterns.
The computer would also need to be compatible regarding SOHC vs DOHC.
You can make a Cali engine work in a Fed car but not so easily the other way around.
There were some late 1999 engines that were 3rd gen, but again a picture would clear that up.

The two biggest differences between 2nd and 3rd gen are as follows:
1. ECU/Harness are completely different between 2nd and 3rd gen:
2nd gen 1996-1999 = Manufactured by Delco
3rd gen 2000-2002 = Manufactured by Motorola
This is the biggest challenge when swapping between the two generations.

2. I don't know about the SOHC but for sure the DOHC has different heads and manifolds (both intake and exhaust) between generations.

These two things alone create challenges with connecting hoses for cooling system, fuel system, brake booster, wiring for sensors, throttle cable, etc.

So let's start with figuring out what exactly you have in that crate before we go much further.

 

Thanks jamnar.

This is The type of sale you can legally defend after the fact, but that doesn't mean all the windows in your house won't be smashed with bricks once a week......

Also, the difference in late 2nd gen / 3rd gen throttle bodies and throttle cables causes problems if I remember correctly.

But let's wait for the pictures

 

1999 crate engine that i have. Notice rounded square exhaust ports

2002 engine. Exhaust ports are "D" shaped and have a hole below each port for the air injector reactor pump.

Based on the factory sticker and labels on the crate, the part number for the crate engine was verified as being for 1999 year models. Based on Saturn parts website, that engine was only offered in 1999 models. I gave a dealership the number for the crate engine and they said yes that is the correct engine for your car. After the purchase, and noticing that the heads were different I did more searching and found that the part differed by one number in the last position between the 1999 engine and the 2000 and up version. I don't know why the dealer gave me incorrect information, but I made the purchase Based on the info I found and what they told me.
From what I can tell, I coykd use the engine in my 2002, but I would lose the catalytic converter that is part of the exhaust manifold, i woukdnt have anywhere to connect thw smog pump and the head pipe for the echaust would have to be modified due to the clocking of the bolts and my stock one being too short. I would need a 1999 head pipe and some modifications to the length.
I just need to know if this would work in a 1997. I have someone interested in it. I was able to find out that their car is an auto trans and is an SL2 which should have the DOHC engine. The Saturn parts website said that the SOHC was also used in SL2 models but I don't know for sure. I thought that was the main difference aside from maybe a rear sway bar and a couple other creature comforts.
Thanks for your reply. Let me know your thoughts on whether it will work in a 1997. I will verify if the guy has a DOHC or an SOHC engine.
Both photos i attached are of the SOHC varietys which i am sure you are aware of. Just wanted to make that clear for others.
Thanks again!

 

I'm not a mechanic and by no means an expert on anything, but I'm pretty sure that a SOHC engine can't just be swapped out for the DOHC. I'm pretty sure there's going to be differences in the wiring harness and various sensors at least, if not substantially more. Jamnar and derf know a LOT more about that stuff than I do.

 

I'm sure that if someone really wanted to swap an SOHC in for a DOHC it can be done but that would require a different wiring harness and a CPU for a DOHC engine along with other parts.
I just need to know if the 1999 SOHC engine i have can be used in a 1997. I really need to recoup the $2500 I spent on it.The only other option I have would be to put it in my 2002 as long as it will work with the electronics. From what I can tell, I would have to use the 1999 exhaust manifold (which I have) as well as add a small cat after it and modify the down pipe to fit the rest of the exhaust system. I will also have to figure out how and where to add the air injector reactor tube. Since it pumps air into my stock manifold just above the catalytic converter, I should be able to make a new tube and plumb it into the system just above the cat on the 1999 set up. I need to be 100% sure the engine will work in my car before I decide to do that. I cannot afford the down time of pulling the stock engine just to find put after installing the 1999 one that it doesn't work

 

As you said, anything can be done. When there's a will there's a way.

But at minimum put this SOHC into a 1997 s car that was a DOHC, you would indeed need

1) 1997 SOHC PCM with automatic transmission
2); Likely The 1997 SOHC under hood wiring harness to make this less painful
3) The air pump didn't come in until after 97 on the DOHC, so if the new engine comes with the air pump attached, he will need to leave it disconnected and plug the lines as I don't believe there is a passage in the block but that exists in the third generation engines
4) mating a 97 SOHC motor to his existing mp8 transmission for the DOHC will result in an interesting shift in the shift points. I expect the TCM to throw constant "incorrect gear ratio" errors since it is expecting to see the gear ratios associated with an MP7 from an SOHC automatic. The cross connection of SOHC and DOHC engines with DOHC and SOHC transmissions, respectively has been done. I believe the vehicles are drivable but I cannot tell you how differently they would drive. The information is on the net but you'll have to dig. And I hate to say this but it was probably on Saturnfans. You can sign up at sixthsphere.com's website or preferably their Facebook group as the site itself does not get much attention. They've basically moved the discussions to the Facebook group. These folks were the people creating their own turbo installations, modifiying anything you could on the car. I have to believe one of them would have done the swap you are trying to do although most people swap from an SOHC to a DOHC for obvious reasons.

5); if it is in early enough 99, then it would need the 97 style SOHC exhaust manifold which I believe has different number of mounting studs and locations than the 97 DOHC equivalent.

6) Believe the intake manifold between SOHC and DOHC is different in general. So he would need an SOHC 97 intake manifold.

7); I believe the fuel rail setup would have to be from a 99 SOHC because the 97 DOHC and 97's in general had a fuel return line to the tank that the 99 and up did not. Also, different injectors in all likelihood.

8) if it is an early enough 99 s o h c, it should still have the horizontal throttle body and throttle cable to match the 97 car. If not and the 99 engine has the throttle body mounted vertically, there's another set of issues to solve.

That's off the top of my head.

If the person you are selling this to is made aware of of this information prior to purchase, knowing how much work will be involved along with the cost to make this engine run properly in the 97 that's one thing.

If the engine is being portrayed as a bolt in and drive, save both of you a lot of trouble and find another buyer or use it in your vehicle..

Once you make that decision, we can figure out whether or not putting it in the 2002 makes sense.