Thinking about a 3GR engine swap from a GS300 - Any tips?

[CiaranMcK]

Hi all,

 

After suspected head gasket failure I’m seriously considering an engine swap from the 2.5 V6 to the 3.0 from a 2006-2011 GS300.

 

From what I can tell it should be plug and play, using the same ECU, manifolds etc with no real downside. 
 

It’s be good to speak to someone with direct real world experience in this swap before I pull the trigger! 
 

Any known complications?

 

Thanks! 

[Linas.P]

Nobody has done this swap before, so I doubt you find much information on that. What I can confirm is that the engine does not use same ECU, in other hand you can get whole GS300 for probably £2000 and from there on it should be mostly plug and play because IS came with this engine and was called IS300. GS300 used different gearbox (A760e instead of A960e), but again so does IS300. In short - if you just get the engine then it will not be plug and play, but if you have entire car (maybe write-off GS is even cheaper - https://www.copart.co.uk/lot/52264852/clean-title-2006-lexus-gs300-se-a-sandy), then it should be fairly straightforward as IS250 body/chassis is identical to IS300 chassis which used same engine and gearbox. 

[CiaranMcK]

45 minutes ago, Linas.P said:

Nobody has done this swap before, so I doubt you find much information on that. What I can confirm is that the engine does not use same ECU, in other hand you can get whole GS300 for probably £2000 and from there on it should be mostly plug and play because IS came with this engine and was called IS300. GS300 used different gearbox (A760e instead of A960e), but again so does IS300. In short - if you just get the engine then it will not be plug and play, but if you have entire car (maybe write-off GS is even cheaper - https://www.copart.co.uk/lot/52264852/clean-title-2006-lexus-gs300-se-a-sandy), then it should be fairly straightforward as IS250 body/chassis is identical to IS300 chassis which used same engine and gearbox. 

Thanks mate

 

Sorry if I wasn’t clear, I’m looking at the 3GR-FSE to replace my IS250s 4GR-FSE. The IS300 didn’t come with the 3GR-FSE I don’t think? Only the Euro GS300 (2006+) and Toyota Crown/Mark X

I’ve seen the engine swap done before, generally people use the 3GR block with the original 4GR intake manifolds, Throttle body etc. They share the same injectors, sensors, throttle bodies etc so the ECU in these cases has worked like normal. The only times they’ve reported needing the 3GR ECU/the 4GR mapped is when they’ve added a supercharger. 

I’ve not heard anyone have issues with the gearbox and engine matching up, but obviously if they’re different units I’ll definitely have to look into that as a potential  issue! I’ve mainly seen this done with 6MT but also a couple of autos too. 
 

If it’s NOT as straight forward as I’ve been LED to believe though, I’ll just put another 2.5L back in. 

[Texas]

Gotta ask….are you saying you have a IS250 ( 2.5L V6 lump) that has had a head gasket fail? as you say ‘suspect head gasket failure’  what makes you come to this conclusion? Symptoms?

cheers Tex.👍

[CiaranMcK]

40 minutes ago, Texas said:

Gotta ask….are you saying you have a IS250 ( 2.5L V6 lump) that has had a head gasket fail? as you say ‘suspect head gasket failure’  what makes you come to this conclusion? Symptoms?

cheers Tex.👍

Air in the coolant, pressuring extremely quickly, eventually getting pressure in the expansion tank and p***ing coolant out of the pressure relief hose in the expansion tank lid. No hot air through the front facing blowers (although I do get it from the foot blowers). No overheating or mayo or anything, so I'm thinking just a very mild leak right now letting exhaust gasses into the coolant.

 

Bled the system a few times and air seems to re-appear. A blockage isn't 100% ruled out yet, but short of removing the radiator and getting access to the heater matrix to check for blockages there I'm out of ideas. 

 

I've asked my MOT garage to check for gas in the coolant system with his exhaust probe to see if we can fully diagnose exhaust gasses in there for now. 

[Linas.P]

Everything was clear for me.

There was Lexus IS300 and IS300 AWD in US, Middle East, maybe Oceania and ruzzia. Maybe South Africa as well. They used 3GR-FE rather than 3GR-FSE (like GS300), but came with A760e, same as 2GR as it is stronger gearbox, but maybe a little bit more lazy on gearshifts than A960e. So the first question - is it possible to put 3GR-FSE in IS250, the answer - yes they came from factory with dimensionally and functionally identical engines.

Now whenever people have used 4GR ECU to run 3GR... I guess everything is possible. Throttle body (I have literally bought GS300 throttle body to replace mine few days back), Coils and injectors indeed seems to be the same, but that does not mean GS300 or 3GR comes with same ECU as IS250/4GR. In either case - if you planning to do it I advise you to buy entire GS300 breaker. There are other nice bits like larger front brakes which you can transfer. 

In either case it seems you know more about this swap than I do, I am not aware of anyone in UK who did this, perhaps you need to check on clublexus or my.is forum in US where they had done more such stuff. 

Otherwise sounds like interesting project and something nicely in between IS250 and IS350 with 248HP.

P.S. Just make sure you actually have blown head gasket, it would be kind of waste otherwise. Head gaskets don't blow on these cars often and this must be 2nd case in over 8 years.

[CiaranMcK]

5 hours ago, Linas.P said:

Nobody has done this swap before, so I doubt you find much information on that. What I can confirm is that the engine does not use same ECU, in other hand you can get whole GS300 for probably £2000 and from there on it should be mostly plug and play because IS came with this engine and was called IS300. GS300 used different gearbox (A760e instead of A960e), but again so does IS300. In short - if you just get the engine then it will not be plug and play, but if you have entire car (maybe write-off GS is even cheaper - https://www.copart.co.uk/lot/52264852/clean-title-2006-lexus-gs300-se-a-sandy), then it should be fairly straightforward as IS250 body/chassis is identical to IS300 chassis which used same engine and gearbox. 

Thanks mate. If I pull the trigger and do it I’ll let you know how it went! If I spend £1000 on an engine and a few days fitting it though it’s still very cheap per HP added! 

 

I keep hearing this scepticism about the head gasket. It’s with a garage at the moment and he’s reluctant to strip it down to definitively diagnose it. I’ve asked him to do a sniff test to be sure. Do you have any tips on how I could fully diagnose HGF without spending hours stripping the engine down? 

[Spock66]

37 minutes ago, CiaranMcK said:

I keep hearing this scepticism about the head gasket. It’s with a garage at the moment and he’s reluctant to strip it down to definitively diagnose it. I’ve asked him to do a sniff test to be sure. Do you have any tips on how I could fully diagnose HGF without spending hours stripping the engine down? 

Sniff test should be conclusive, otherwise a compression test if the plugs are reasonably accessible.

[Texas]

Trouble is they are Not! 50% of them anyway!

[CiaranMcK]

10 minutes ago, Texas said:

Trouble is they are Not! 50% of them anyway!

Yeah exactly this. Could compression test the 2 or 3 that are easy enough to get to, but realistically I’d need to strip it down to get to the spark plugs to fully diagnose. 
 

If it passes sniff test maybe I’ll go that way. But by that point I might as well just have an engine waiting to pop in. 
 

Out of interest - would you sniff test from the thermostat or the expansion? 

[Linas.P]

2 hours ago, CiaranMcK said:

Yeah exactly this. Could compression test the 2 or 3 that are easy enough to get to, but realistically I’d need to strip it down to get to the spark plugs to fully diagnose. 

Removing the plenum to access sparkplugs is 15 min job max, 5mm hex, 10mm and 13mm sockets and that is job done. Apart of 1 annoying bolt behind the throttle body the rest takes literally as much as it takes to unscrew the bolts. I have done it like 8 times just last week (I rather not to, but such is life). 

[CiaranMcK]

12 minutes ago, Linas.P said:

Removing the plenum to access sparkplugs is 15 min job max, 5mm hex, 10mm and 13mm sockets and that is job done. Apart of 1 annoying bolt behind the throttle body the rest takes literally as much as it takes to unscrew the bolts. I have done it like 8 times just last week (I rather not to, but such is life). 

I don’t have a compression tester, but with it being that straight forward I can’t imagine why the garage is so reluctant to do it. 
 

If they don’t I’ll just buy a kit! 
 

Thanks! 

[H3XME]

I wouldn't bother swapping this car. I'd do a straight swap - another 4GR-FSE or go balls deep and swap something worthwhile in it.. otherwise you're wasting a lot of time n money for a very little gain that will not be worth it in the end. Even 2GR swapping it isn't that easy. Well.. suppose it's it's just as easy as 3GR swap but why. I'd rather source a 2GR if I was to do this. Or better yet.. 1UZ. Small lightweight V8 that'll be at home in this bay. Standalone ECU, custom mounts and you can even easily and fairly cheaply get flywheel adapters for BMW ZF manual box. That's what the drifters do. 280hp 270ft/lbs IS250 with a V8 soundtrack would be nice. Call it an IS400 😉

[Linas.P]

26 minutes ago, H3XME said:

Call it an IS400 😉

That what IS-F test mule was called at some point. Later it was bored out to 5L and called IS500. 

Reason for 3GR - the whole GS300 is cheaper than naked 2GR, as well there is no supply of 2GR in Europe and especially UK, whereas there are plenty 3GRs/GS300s. As well it seems to be "plug an play" as long as you have whole package from GS300, hence I would insist on getting whole car or at least half-cut. 1UZ sounds great on paper, but as you mentioned this will require standalone ECU, custom mounts, custom gearbox solution etc. And it is little bit antiquated engine to be honest, better choice would be to go with 3UZ 4.3L unit, they are cheaper, supply is better, they are VVTi, more fuel efficient, more powerful etc. Would still require custom mounts, but if one goes to trouble fitting V8 I would say 3UZ is the way to go. Although again, then one probably should look for old GS430 or SC430 as a whole donor car rather than naked engine, because standalone is much more difficult on 3UZ compared to 1UZ. 

Anyway going back to 3GR, the reason it would make sense - the cost and availability, it would not cost much more than getting another 4GR, but it offers nice 50hp bump. Now of course - swapping working 4GR to 3GR would be madness, but if indeed the engine on OP car is dead and needs replacing, then I think this isn't bad idea.

[H3XME]

15 hours ago, Linas.P said:

That what IS-F test mule was called at some point. Later it was bored out to 5L and called IS500. 

Reason for 3GR - the whole GS300 is cheaper than naked 2GR, as well there is no supply of 2GR in Europe and especially UK, whereas there are plenty 3GRs/GS300s. As well it seems to be "plug an play" as long as you have whole package from GS300, hence I would insist on getting whole car or at least half-cut. 1UZ sounds great on paper, but as you mentioned this will require standalone ECU, custom mounts, custom gearbox solution etc. And it is little bit antiquated engine to be honest, better choice would be to go with 3UZ 4.3L unit, they are cheaper, supply is better, they are VVTi, more fuel efficient, more powerful etc. Would still require custom mounts, but if one goes to trouble fitting V8 I would say 3UZ is the way to go. Although again, then one probably should look for old GS430 or SC430 as a whole donor car rather than naked engine, because standalone is much more difficult on 3UZ compared to 1UZ. 

Anyway going back to 3GR, the reason it would make sense - the cost and availability, it would not cost much more than getting another 4GR, but it offers nice 50hp bump. Now of course - swapping working 4GR to 3GR would be madness, but if indeed the engine on OP car is dead and needs replacing, then I think this isn't bad idea.

Well, the RX450h is 2GR isn't it.. only with hybrid, but the engine alone would be alright, but yes I agree 3GR would be a little cheaper, perhaps easier too.

[Linas.P]

1 hour ago, H3XME said:

Well, the RX450h is 2GR isn't it.. only with hybrid, but the engine alone would be alright, but yes I agree 3GR would be a little cheaper, perhaps easier too.

Not really, both RX and GS450h has 2GR-FXE, which is clearly a "2GR", but not THE "2GR". As far as physical appearance goes they are very similar, but it is tuned completely differently (278hp) and attached to CVT, one further complication on RX is that on RX engine is mounted transversally and mounts to body via gearbox/transaxle. So that means it will require standalone ECU +£1000, and it may require custom brackets for starter etc (because hybrids don't have the standard starter) and in case of RX it will require all custom mounting as well... so at that point UZ is definitely better way to go. 

Point being - crashed IS250/GS300 can be bought for £800-£1500 for compart with all parts needed for swap, GS450h and RX450h will be more like £2000-£3000 because a lot of people bidding high for batteries, + they will require standalone ECUs or will only make 278hp + RX will require custom mounts + custom starter bracket. GS430/SC430 again could be had for probably £2000 and they will only require custom engine mounts. At some point I was wondering how IS450h would drive, meaning taking GS450h with the hybrid part, but that is complexity on the whole other level.

[CiaranMcK]

OK - so I didn't go ahead with this as the car was actually a simple fix - the pipe leading from the Thermostat to the expansion tank, and then from expansion tank to nothing seemed to be the problem. I can't explain why, but once I changed this with another it stopped losing coolant immediately. 

I did all the research though, and the swap is 100% viable, and probably the cheapest way to add c50bhp! 

[SeanR]

Might be doable but seemed a lot of hassle for 50bhp.

Id be so glad it was just a pipe .

[Texas]

Pretty rare for a HG to go on a 250, a 220 now you’re talking!

”P.S. Just make sure you actually have blown head gasket, it would be kind of waste otherwise. Head gaskets don't blow on these cars often and this must be 2nd case in over 8 years.” Linas.P

so back down to 1 case then😀

[CiaranMcK]

5 hours ago, Texas said:

Pretty rare for a HG to go on a 250, a 220 now you’re talking!

”P.S. Just make sure you actually have blown head gasket, it would be kind of waste otherwise. Head gaskets don't blow on these cars often and this must be 2nd case in over 8 years.” Linas.P

so back down to 1 case then😀

Yep! 
 

First garage diagnosed head gasket. Lex Tech initially diagnosed head gasket too, but the more he looked for confirmation the less he thought it was actually head gasket! 
 

It turned out to be this, at some point it has been put on backwards. There must be a directional valve in the cap, or just some sort of pressure difference with the different lengths of hose on either side. 
 

 

[Linas.P]

13 minutes ago, CiaranMcK said:

Yep! 
 

First garage diagnosed head gasket. Lex Tech initially diagnosed head gasket too, but the more he looked for confirmation the less he thought it was actually head gasket! 
 

It turned out to be this, at some point it has been put on backwards. There must be a directional valve in the cap, or just some sort of pressure difference with the different lengths of hose on either side. 
 

 

Wow. Imagine swapping engine for that! 😄

[CiaranMcK]

Honestly!
 

Even the Lexus specialist didn’t think it would be that. They fully thought head gasket. It just happened they had some parts on the shelf so did some swapping as a last resort. We were gobsmacked when it did the trick. 

[Texas]

16 hours ago, CiaranMcK said:

Yep! 
 

First garage diagnosed head gasket. Lex Tech initially diagnosed head gasket too, but the more he looked for confirmation the less he thought it was actually head gasket! 
 

It turned out to be this, at some point it has been put on backwards. There must be a directional valve in the cap, or just some sort of pressure difference with the different lengths of hose on either side. 
 

 

You can see that one external hose goes to the long ‘dip’ tube and the other external hose just goes to cap.

After a heat cycle of the engine the coolant in the engine ( whole system actually ) will cool and contract, this contraction will draw  some coolant ( via the dip tube) from the ( non pressurised) external reservoir. If the reservoir is empty or in your case the system was trying to draw from the cap hose) then it is going to draw in air and cause your low coolant problem over time. There is no valve but direction of hoses is important part.

[is2503grfse]

I have 3grfse swap in is250 manual I can guide you through the process. It is plug and play excepf maf sensor air box section and cable for reverse light from gearbox. Tune is advisable to compensate for different fuel map.

[Linas.P]

On automatic car you don't need to map anything, just use GS300 (3GR-FSE) ECU. Obviously, I understand you having manual car that was not an option as there was never manual XX300. That said - how do you get IS205 ECU mapped, or you run aftermarket ECU?