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Hello all. Just recently purchased a 98 trans am. Took to mechanic shop for a temperature gauge repair. The mechanic told me I did not have original 5.7 engine but couldn’t verify what engine I had. I’ve only had the car less than a month. Runs great, drives great. Powerful as hell. I honestly don’t care which engine it is but was not told at time of sale and that bothers me if true. I just want to know so I can move forward if there is anything I want to work on. Is there any ways to find out besides serial numbers because I cannot find those or they are too hard to find because of engine being inside car. It has 806heads , aluminum block. Every part that I can find a serial number to belongs to a 5.7.
what is the best way to find this information out. Thank you all In understand it’s just a photo. Just wanted to give any help I could
Well, if it's an aluminum block, you probably do have the LS1 5.7.
The aluminum block 5.3 was only produced a few years and few models and I would say they are pretty rare (all other "common" 5.3s were used in trucks, SUVs and some vans and are iron block.)
Why did the mechanic think it was not the original 5.7L?
806 heads are correct for the 1998 LS1, as is the aluminum block. So what piece or pieces made him think the engine had been swapped out?
The picture you posted above is very small, but everything looks to be in order from what I can tell. I even see an EGR tube still; it's unlikely anyone would have retained EGR if they did an engine swap (unless it needed to be emissions compliant, in which case it would likely be a factory replacement engine of the same displacement).
FWIW, if your mechanic is basing his assumptions on anything to do with the temp gauge repair, the issue might have to do with the fact that 1998 used a one year only temp sender. If he's used to seeing the typical '99+ piece, that might be why he thinks it's the wrong engine. But if your heads are stamped as "806" then they are definitely the correct heads at least.
Why did the mechanic think it was not the original 5.7L?
806 heads are correct for the 1998 LS1, as is the aluminum block. So what piece or pieces made him think the engine had been swapped out?
The picture you posted above is very small, but everything looks to be in order from what I can tell. I even see an EGR tube still; it's unlikely anyone would have retained EGR if they did an engine swap (unless it needed to be emissions compliant, in which case it would likely be a factory replacement engine of the same displacement).
FWIW, if your mechanic is basing his assumptions on anything to do with the temp gauge repair, the issue might have to do with the fact that 1998 used a one year only temp sender. If he's used to seeing the typical '99+ piece, that might be why he thinks it's the wrong engine. But if your heads are stamped as "806" then they are definitely the correct heads at least.
I wasn’t sure about why he said it wasn’t the 5.7 because I got flustered when he told me it wasn’t. He told me that if I was to go out right now and buy parts for a 98 trans am, none of them would fit because this engine, he feels is from the later 2000s. He said this was “piecemealed” together I took it from the shop before he could say anything else because I feared they were trying to screw me.
I’m thinking that the mechanic was not on his game that day but I’m worried about changing the oil or small things like that. Hoping this closer picture will help
...I took it from the shop before he could say anything else because I feared they were trying to screw me.
Yeah, I think you made the right call there.
Nothing looks "piecemealed" in that picture. You have the correct 806 heads with perimeter bolt valve covers (this was gone starting in 1999), I can see the factory EGR is present so the intake is likely correct, and even the throttle body appears to be correct for a 1998 (vs. the later one with a different cam). Only thing out of place is the location of the PCV tube (it's not really "out of place" exactly, it's in the right area, it's just sitting on top of things when it should be tucked down closer to the intake - but it still appears to be the correct 1998 tube based on the location of the valve), and the radiator cap is not original (no big deal there). Also, the shock tower nuts are not original (they would have been gold colored from the factory, those look like fresh replacements), and there was a brace/bracket going from the AC line near the passenger side shock tower that would have been bolted to said shock tower originally (I've only ever seen this on a 1998) which is also missing (again, no big deal).
I can't imagine what that shop was talking about. I would stay away from them going forward.
You certainly know what you’re talking about in minute details. Appreciate the time you put in answering my question.
Originally Posted by RPM WS6
Yeah, I think you made the right call there.
Nothing looks "piecemealed" in that picture. You have the correct 806 heads with perimeter bolt valve covers (this was gone starting in 1999), I can see the factory EGR is present so the intake is likely correct, and even the throttle body appears to be correct for a 1998 (vs. the later one with a different cam). Only thing out of place is the location of the PCV tube (it's not really "out of place" exactly, it's in the right area, it's just sitting on top of things when it should be tucked down closer to the intake - but it still appears to be the correct 1998 tube based on the location of the valve), and the radiator cap is not original (no big deal there). Also, the shock tower nuts are not original (they would have been gold colored from the factory, those look like fresh replacements), and there was a brace/bracket going from the AC line near the passenger side shock tower that would have been bolted to said shock tower originally (I've only ever seen this on a 1998) which is also missing (again, no big deal).
I can't imagine what that shop was talking about. I would stay away from them going forward.
That engine bay looks real untouched. Not saying that’s the end all be all but based off everything else I agree with the others that there’s nothing that shows it isn’t.
side note: man I forget how cramped those engine bays are stock
You certainly know what you’re talking about in minute details. Appreciate the time you put in answering my question.
Glad to help.
I really can't imagine what that shop was trying to accomplish by attempting to convince you that the engine was some sort of Frankenstein creation, but I just can't see anything in that picture (or in what you mentioned about head casting numbers and block composition) that would even remotely suggest such a thing. Either they have some sort of unscrupulous intention, or they just don't know these cars very well.
It amazes me how many "mechanics" don't know squat about cars. Some shops are so hard up for help they'll hire nearly anybody, and you end up with guys talking out of their *** about things they have zero clue about. I have a '98, and your engine compartment looks dead stock. RPM was spot on in his observations. The only issue you'll ever run into is if you decide to upgrade your cylinder heads, you'll have to buy a pair of center bolt valve covers because the ones you have are specific to those heads and no one really modifies those.
Thank you. I’ve looked at many pictures of 98 ls1 engines in the trans am and they all look identical to mine. And yours it sounds like. I am not a guy with enough knowledge to tell things like this but all sounds like the mechanic didn’t know what he was talking about. I have a question for you, I have a knock sensor 2 circuit low. Is this common and how important are the knock sensors ? Sometimes the ses light goes off and sometimes it comes back on. Thank you for replying to my original post.
Originally Posted by LS1Formulation
It amazes me how many "mechanics" don't know squat about cars. Some shops are so hard up for help they'll hire nearly anybody, and you end up with guys talking out of their *** about things they have zero clue about. I have a '98, and your engine compartment looks dead stock. RPM was spot on in his observations. The only issue you'll ever run into is if you decide to upgrade your cylinder heads, you'll have to buy a pair of center bolt valve covers because the ones you have are specific to those heads and no one really modifies those.
I have a question for you, I have a knock sensor 2 circuit low. Is this common and how important are the knock sensors ? Sometimes the ses light goes off and sometimes it comes back on. Thank you for replying to my original post.
You might want to check out this thread (and the links contained within) on knock sensors:
It's a bit difficult to get a proper-functioning replacement knock sensor for this engine these days (all brands are NOT created equal). Before embarking on this repair, check out all the info in the above link.
Definitely a 1998 LS1. Perimeter Valve Covers, as mentioned, are clear as day to those of us that know what to look for.
Your 1998 Temp Sensor is a 3-Pin Sensor that's one year only. GM Part #12551708.
I have that memorized because of the dozens of LS Swaps I've had my hands in that is the Temp Sensor used to get the factory GM Electronic Temp Gauge to work when you wire in the LS PCM.
Fire that "mechanic" and tell him we said he needs to learn some stuff before calling himself one.
It amazes me how many "mechanics" don't know squat about cars. Some shops are so hard up for help they'll hire nearly anybody, and you end up with guys talking out of their *** about things they have zero clue about.
Originally Posted by the_merv
Fire that "mechanic" and tell him we said he needs to learn some stuff before calling himself one.
06-13-2024, 05:54 PM
Trying to figure out if I have a 5.7 or 5.3 swap 
