GTP engine problems

[GTPer]

I have a 97 GTP that has had 3 different motors put in after the original started knocking. All the other three also started knocking but the second engine lasted a week, the other two not even a day. I don't know what the problem is. I don't believe all three engines were bad from the junkyard could they?. What could possibly be the problem? It's causing my mechanic too much work. And me too much waiting. I would really appreciate any feedback as to what the problem could be.

[vipmiller803]

Sounds a lot like what I went through. Unless he is opening them up, then as is JY engines are pretty much big gambles, especially after this long, especially L67's. Every time I replaced mine it would look okay to me, then knock and have oil pressure problems after the install. If I had to do it over, I would rebuild for sure... At least you know what is going in then.

The only things that are common are your cooling, your fuel, and your ignition (maybe). Cooling - no way. Fuel - Highly unlikely, unless you put water in there, in which case many more symptoms like running like shit (if it even starts) would be an issue besides the knocking. Ignition - I guess depends on if he is keeping what comes with the engines or the original. Still would be very unlikely with the "new" knock sensors. No oil cooler to be filled with crud (to my knowledge anyways).

[Nas Escobar]

I would suggest an S3 block at this point and put your S2 accessories on the block.

 

As to what's causing it, it's hard to tell. As VIPMiller said, JY engines are a gamble. I went through it myself with my Camaro, I had looked at 5 engines, bought one that was bad and ended up with an S3 block.

 

Does he still have your original engine or was it cored out?

[GTPer]

The original engine was cored out. The first engine he got had a three month warranty so he's gotten the other two for free. I'm pretty sure he just transferred all of the parts from the original engine to the new blocks. What do you mean by s3 block and s2 accessories? It's just frustrating that he spends weeks on each overhaul and it doesn't come out right.

[Schurkey]

It's just frustrating that he spends weeks on each overhaul and it doesn't come out right.

Is he overhauling them, or replacing them? I thought he was replacing the defective engines.

[GTPer]

The original engine knocked but was still driveable it could only hit like 20mph though. He replaced that one and he said it started knocking when he was pulling out of the shop. The last engine he pulled I think had a hole in the block. I would put oil and it all just poured out on startup. Literally all the oil in a couple of seconds. And now the third engine he said it started up just fine but started knocking after a while.

[GTPer]

Is he overhauling them, or replacing them? I thought he was replacing the defective engines.

 

Oh sorry I meant replacing. He's replacing the engines. Not overhauling. An overhaul is basically a rebuild right? Now my mechanics suggesting a rebuild instead.

[vipmiller803]

What do you mean by s3 block and s2 accessories? It's just frustrating that he spends weeks on each overhaul and it doesn't come out right.

Series 3 block. Those came out in later years than yours. They have slightly better internals and improved intakes/gaskets, but mostly they are better because they are newer and more readily available not already destroyed. I would wonder if your mechanic would even be willing to put anything not stock in. I also would wonder if the super charger would complicate such a swap. Nas did not have to mess with that because his is N/A.

 

Weeks... seems a little long. He should be good at it by now!

[Nas Escobar]

The original engine was cored out. The first engine he got had a three month warranty so he's gotten the other two for free. I'm pretty sure he just transferred all of the parts from the original engine to the new blocks. What do you mean by s3 block and s2 accessories? It's just frustrating that he spends weeks on each overhaul and it doesn't come out right.

 

I ask because it would have been ideal to know what caused the knock on the original engine. I'm not saying this is computer related but I am saying that it's rather strange that this keeps happening.

 

For you to understand what I meant by "S3 block and S2 accessories", you have to realize there were 3 versions of the 3800. 4 if you count the first engine branded as a "3800" and 5 if you count the transverse mounted 3.8 LG2 & LG3. I'm pretty sure you've heard the stories that the 3800 is a Buick 90 degree engine based on a V8 Buick design from the 60's and has been updated as time went by. I'm not gonna post a full book on here, if this interests you then you can look it up for yourself. However, what's relevant here is that there was 4 versions of the 3800. There is a "pre series engine" which was used in from 1988 to 1991, there is a Series 1 engine (or S1 for short) that was made from 1992 to 1995, there is the Series 2 (S2) which was made from 1995 to 2005 and there is the Series 3 (S3) that was made from 2005 to the 3800's demise in 2008. Since your car is a 1997, you have the S2 version of the 3800. On your engine cover, it should say "3800" in big letters followed by "Series 2" under 3800 and a larger script font that says "Supercharged". Now what some know, others don't and a lot refuse to divulge into is that the Series 3 kept the same block and sensors as the Series 2. You can't swap between the L26 (what replaced the L36 AKA the 3800 S2 naturally aspirated) and the L67 HOWEVER you can get an engine out of a 2004-2007 Pontiac Grand Prix GTP or GT. The engine RPO code that replaced the L67 is the L32. Now you would have to swap over the S2's upper intake manifold (plenum), the fuel rails, and the throttle body but everything else is a direct bolt on. What basically changed on the S3 was a better head design (bigger exhaust valves), better connecting rods (on the Naturally aspirated engine anyways), returnless fuel injection (which is why you have to use your current injectors) and electric throttle (which is why you have to use your S2 plenum and throttle body). In regards to your supercharger, you have to use your S2 supercharger and bolt it on to the donor engine.

 

This is why I suggest you get an L32 (3800 Series 3 supercharged). It is a newer engine, it was the final revision with all the "kinks' worked out on the engine, and there's a better probability that the engine will not be abused or with high mileage. This is another thing worth asking... is your mechanic verifying that these engines aren't junk? A simple valve cover pull will verify how well it was maintained. I would also suggest that the mileage stays below 90k.

[GTPer]

I'm not sure if he checks the engines but he has told me that every engine he's put in has had 100k or less miles. Would it be worth buying a l32 block and swapping that stuff over? Or just rebuilding the l67? I haven't asked him how much the rebuild will cost but I'm sure an l32 block will not be cheap or easy to come by. And are you sure the intake manifold, rails, throttle body and supercharger are all transferable to the l32 block, I've never heard of a gen 3 supercharger on a l32 block. I've only heard of a gen v supercharger on an l67 block and theres a lot of work to that.

[jman093]

If you're sure your mechanic is competent, which is always the first thing I question in something like this, there could be chunks of ruined engine in the intake manifold/supercharger. When an engine lets go, they sometimes deposit metal in the intake. I have no idea how it goes up backwards against airflow; one would think it would all go out the exhaust end, but they do. This is why a lot of new/reman long blocks come packaged with screened intake gaskets like this in the crate:

 

 

The idea is to catch the shards and chunks from going back down the engine. No idea if this actually work. Shards big enough to do damage are still gonna fit through that.

 

I've personally seen one mechanic replace 4 or 5 reman long blocks that didn't last even a day because of this. When he finally put a new intake on with the engine, it lasted fine.

[GTPer]

If you're sure your mechanic is competent, which is always the first thing I question in something like this, there could be chunks of ruined engine in the intake manifold/supercharger. When an engine lets go, they sometimes deposit metal in the intake. I have no idea how it goes up backwards against airflow; one would think it would all go out the exhaust end, but they do. This is why a lot of new/reman long blocks come packaged with screened intake gaskets like this in the crate:

 

 

The idea is to catch the shards and chunks from going back down the engine. No idea if this actually work. Shards big enough to do damage are still gonna fit through that.

 

I've personally seen one mechanic replace 4 or 5 reman long blocks that didn't last even a day because of this. When he finally put a new intake on with the engine, it lasted fine.

 

So your saying check the intake manifold and the supercharger? Ill have him do that. Thanks.

[GTPer]

I was going to tell him to check the supercharger and intake manifold but he says that each motor he gets comes with an intake manifold and supercharger already. So he isn't swapping the manifold/supercharger from engine to engine.

[03blackgsx]

He needs a new source for motors. Those motors are probably junked motors for a reason. Not verified running before pulled.

[GTPer]

Yeah he said he was going to look into some other place that said that it was guaranteed the motors run. But could it possibly be something else like the transmission maybe? Before the engine screwed up. I noticed that the car shook off idle. Like going from a stop sign or red light when I let off the brake the car would shake/limp forward. Then had very light knocking and grew louder gradually. It would stop knocking when revved and started knocking again when the rpms dropped back down. Both the engine and transmission had 187000 miles.

[03blackgsx]

You need to have a solid starting point. Either the motor or trans need to be working so you can eliminate the other.

LKQ had decent prices on motors. Local junkyards are a huge gamble.

Get your motor running then look for any possible issues with the transmission

[vipmiller803]

Yeah he said he was going to look into some other place that said that it was guaranteed the motors run. But could it possibly be something else like the transmission maybe? Before the engine screwed up. I noticed that the car shook off idle. Like going from a stop sign or red light when I let off the brake the car would shake/limp forward. Then had very light knocking and grew louder gradually. It would stop knocking when revved and started knocking again when the rpms dropped back down. Both the engine and transmission had 187000 miles.

Did this knocking you speak of happen at all temperatures? Was it okay cold but much louder when up to temp for a while? What you describe can easily be a rod knock. The shake/limp... could have been a misfire?

Anyway, is it possible that the trans is the culprit? Sure, but it is unlikely given the history and I assume the mechanic ruled it out. Usually you can modulate the knock from an engine by grounding individual ignition wires one at a time. The lack of power on the power stroke makes the bearings not pound so hard. That is one of many ways to know it is definitely the engine, and usually which cylinder is the problem. Either way, he got it to stop with one of the engines for a week. That alone should rule out the trans. I would ask him if he is willing to do an S3 swap and how much a rebuild would cost, then go from there.

[GTPer]

Yeah I'm probably going to go for the rebuild. I'm just hopefully going to get the money back from the motor and use it for the rebuild. I really don't want to dump much money into the car anymore. An s3 swap would be great if I planned on keeping the car but I just want to get the car running and then sell it and forget about it. It's funny that everywhere I looked it said the l67 is bulletproof, very reliable engine and yet I didn't even put 2500 miles on the car before the motor went.

[vipmiller803]

It really is much more bulletproof than a whole lot of other engines, but it still is an engine. If you mistreat it enough, it will destruct. If you are just trying to sell it, then a rebuild is going to be a huge chunk of your selling price. That would not be my course of action.

[GTPer]

It really is much more bulletproof than a whole lot of other engines, but it still is an engine. If you mistreat it enough, it will destruct. If you are just trying to sell it, then a rebuild is going to be a huge chunk of your selling price. That would not be my course of action.

 

I really don't have a choice. The junkyard engines haven't worked. Besides I already have a head start on paying for the rebuild. I'll just get the money back from the junkyard and use that toward the rebuild. Or would you recommend something else?

[vipmiller803]

It would really depend on the shape of the rest of the car. If it will not bring good money after the rebuild, I would seriously consider selling it as it, with whatever crap motor it has. You could also give the JY engines one more try and just make sure the engine is thoroughly checked out before the install...

[primergray]

The flexplate in the Monte was cracked one time...sounded an awful lot like a rod knock except it was only at startup and some other random times.

[Nas Escobar]

I'm not sure if he checks the engines but he has told me that every engine he's put in has had 100k or less miles. Would it be worth buying a l32 block and swapping that stuff over? Or just rebuilding the l67? I haven't asked him how much the rebuild will cost but I'm sure an l32 block will not be cheap or easy to come by. And are you sure the intake manifold, rails, throttle body and supercharger are all transferable to the l32 block, I've never heard of a gen 3 supercharger on a l32 block. I've only heard of a gen v supercharger on an l67 block and theres a lot of work to that.

 

If you can get your old engine back, I would highly suggest a rebuild but otherwise, your engine is gone and you need to move forward from it. That's why I suggest an L32 block with your L67 accessories. You just need to make sure the engine is guaranteed good.

 

As finding them goes, they're quite easy to find. I got my L26 from eBay, and it was a local junkyard that was selling it. It was the best decision I made in my situation. I'm definitely sure that all accessories from your L67 will swap to the L32. I had to do it with my Camaro. I have an L26 block in it with all the Camaro specific engine block accessories. Runs quite good actually. Took me a day to get the L26 that I got out of a 2008 Buick Lacrosse to go Camaro spec but it was worth it.

 

AFAIK it's not a gen 3 s/c, it's simply an Eaton s/c for the 3800. It was just revised for S3. I believe you're referring to a Gen V SBC supercharger, which is quite different than what I'm talking of. You're talking of a major mod, I'm simply talking about using a newer 3800 but using your car's specific accessories to make it work. You have it quite easy compared to mine, because AFAIK you can use the S3 LIM with the S2 plenum and S/C whereas I had to strip down to long block status.

[GTPer]

The flexplate in the Monte was cracked one time...sounded an awful lot like a rod knock except it was only at startup and some other random times.

 

I'm kind of a noob but the flex plate is bolted on to the transmission not the engine right? Cuz if it is I'll have the mechanic check it. Thanks.

[GTPer]

If you can get your old engine back, I would highly suggest a rebuild but otherwise, your engine is gone and you need to move forward from it. That's why I suggest an L32 block with your L67 accessories. You just need to make sure the engine is guaranteed good.

 

As finding them goes, they're quite easy to find. I got my L26 from eBay, and it was a local junkyard that was selling it. It was the best decision I made in my situation. I'm definitely sure that all accessories from your L67 will swap to the L32. I had to do it with my Camaro. I have an L26 block in it with all the Camaro specific engine block accessories. Runs quite good actually. Took me a day to get the L26 that I got out of a 2008 Buick Lacrosse to go Camaro spec but it was worth it.

 

AFAIK it's not a gen 3 s/c, it's simply an Eaton s/c for the 3800. It was just revised for S3. I believe you're referring to a Gen V SBC supercharger, which is quite different than what I'm talking of. You're talking of a major mod, I'm simply talking about using a newer 3800 but using your car's specific accessories to make it work. You have it quite easy compared to mine, because AFAIK you can use the S3 LIM with the S2 plenum and S/C whereas I had to strip down to long block status.

 

Yeah he's going to try and get the original engine back and just rip it open see what went bad. I meant the supercharger in the l32 is an eaton gen 5 m90 and the one in the l67 is a gen 3 m90 and the gen v was bigger correct? You got an l26? So your saying either the series 3 n/a or series 3 supercharged block will work?