DIY engine replacement in a Gen 2...

Dear all,
I've occasionally used Prius Chat for a number of years hand have found it very helpful... though I have never posted anything, until now.

Swamp - 1 is a 2005 European (I live in the UK) Gen 2 with 262,500 miles on the clock, which I have owned from new. She is right hand drive and, amongst other things, has rear disc brakes & a large space where the coolant heat recovery cylinder appears in the US model. Unfortunately in November, she developed a rather unfortunate over heating problem, losing a lot of coolant. This was accompanied by increasing misfires on cylinder #3. Sadly this was diagnosed as a blown head gasket - which I decided to replace myself.

Swamp - 1 was progressively disassembled to get to the offending head gasket. Now, this particular car I converted to LPG two years ago, so the intake manifold, airbox etc had all been off before & came off without a fight.The washer bottle, fuel rail etc came off and the brake fluid reservoir was unbolted and turned aside.

The rocker cover came off for the first time since the car was manufactured, and the valves were glistening with motor oil. Valve clearances were checked, and whilst a little tight were only just out of spec - not at all bad considering the mileage. (There is a picture later - though note I am in the UK, so it's all in mm!)

All of the engine left hand side auxiliaries came off - water pump, drive belt, crankshaft pulley etc. No issues. To remove the pulley without the use of the SST, I jammed it against the crank case with a 6.5mm drill bit, having broken 4 M6 bolts.

The 'difficulties' then began. First problem was attempting to use the service mech to release the overhead cams. As much fun as I was having with my 3mm drill bit and carefully selected spanners (you don't need the SST - honest!) I couldn't really get the cam change to retract enough to get the sprockets out. So, off came the timing cover. (It has to come off anyway, but I wanted to try out the adjustment procedure along the way). Watch out for the M6 bolt in the centre of the cover in the recess is all I can say. It was quite difficult to pry off. The FIPG held on firm!

With the timing cover off, releasing the cam chain tensioner was extremely easy (benefits of being able to see what you are doing!) Both cam chain guides came off easily, along with the sprocket & both overhead cam shafts. The fittings for the cam shafts were all stamped (by Toyota) with their positions & laid out neatly on the shelf in order. The cam chain came off - interestingly it was not positioned using the coloured links - I guess this is because the robot in the factory which puts it on cannot see, but uses knowledge of the shaft positions to align everything. The valve lifters also came off without trouble.

With the timing gear off & all hoses & electrical connectors disconnected & labelled, it was time to remove the engine head. Another problem - the head bolts use M10 splined driver - I ordered some more tools. Always the sign of a new job!

A couple of days later the long bolts came out, no issues. At this point, with the exhaust manifold attached (due to one stuck and now rounded off bolt) and disconnected from the exhaust, the head pulled off quite easily. The gasket had clearly failed between the water jacket & cylinder #3 where #3 joins #2. There was also evidence of wear between #1 & #2 and #3 & #4, though these had not yet failed. #1, #2 & #4 were quite carbonized. #3 was shiny & clean - evidence of a good steam bath recently!

Now, prior to re-assembly, the aluminum head needed a skim, so, after a bit of a ring around off I went to Hurley Engines in Bath. Alas it was not to be - the helpful gentleman who called me that afternoon had found damage to both exhaust valves on cylinder #3 - not very good. Looking closer (I'm only a DIY person) there was also clearly damage to the top of the piston & the cylinder head in #3. His opinion was that a piece of piston ring or piston wall had parted company with the piston & left the cylinder via the exhaust valves... it seemed reasonable. Either way, not a lot of point putting it back together with two exhaust valves which don't seal. So, I collected my now disassembled (valves out) engine head and continued to attempt to remove the engine.

Next job was to attempt to remove the drive axles. As I suspect readers of this forum know - on this car, the engine comes out of the bottom, attached to the transaxle. In order to do this, both drive axles have to come out. I completely removed the steering knuckle for access (it really is much easier). The steering gear detached with a sharp strike of the hammer. Unfortunately the instruction to 'gently pry the inner CV joint' out of the differential with a crowbar was a bit too difficult, and unfortunately both drive axles were removed by separating the inner CV joints. One inner CV joint half each side being left rather firmly attached to the differential.

Removing the power electronics on the other hand was straightforward. Following the excellent instructions, I removed the safety plug from the HV battery, unplugged the HV battery connections from the hybrid drive, drained the coolant down (a nice bright pink) and took the lid off. Inside there were 3 small wiring connections to undo and the two motor generators. Having proved not live with the multimeter, I unbolted the 3 phase connectors from each MG and pulled the connections out. There are two more mechanical bolts on the outside. Three coolant hoses were removed (including the front bleed valve), three more small electrical connectors from the rear and one from the right side, the three mounting bolts were undone and the power electronics lifted off.

Numerous small wiring connectors and hoses were then undone and the engine & transaxle were checked all the way around to be clear of all connections. The air conditioning compressor came off by removing 3 bolts & was hung beneath the radiator still gassed up.

A couple of interesting points here. The reason you can't lift the engine & transaxle out of the top of the car (we had a big engine hoist - see pictures) is that one stainless aircon pipe passes across the car from front to rear in the middle & remained gassed up. Also, the brake fluid master cylinder & a myriad of micro bore pipework is in the way above the transaxle. I wouldn't mind, but, as we were in my home garage with no vehicle lift, out the bottom was looking creative. The timing cover was re-attached with the water pump pulley bracket as a lifting point. This also covered the timing gear as the next part was rather awkward.

Now for the next part I had a friend - this was extremely helpful! The engine & transaxle were attached to the engine hoist & spreader bar. The spreader bar can be wound to the left or right once loaded, to account for our 'guessing' the centre of gravity of the load. The central engine support was also removed. It was only necessary to remove the two bolts underneath the engine & the two from the suspension - the central bolt we couldn't shift & didn't need to. The transaxle support is a single, central bolt. The engine hoist took some weight and this was undone, leaving the transaxle end floating on the hoist. The engine end a combination of bolts were undone until the mount seperated from the chassis. A lot of wiggling was required and the engine end rose and the spreader bar was evidently not set correctly for the load!

Having all but levelled the load, we attempted to lower it onto a board between the legs of the engine hoist - also doubling as out engine removal trolley. Unfortunately, the engine & transaxle would not fit through the available space. We removed the radiator mounting bracket (top) and stepped the radiators forwards to increase clearance. We also removed a transducer from the back of the transaxle to make it thinner. Then, with the engine end of the assembly held high, we lowered the wider transaxle end through the space and onto the board, and then lowered the narrower engine end to the board. Another important point - there is a final electrical connector from the loom on this transducer - I couldn't remove it until we had part lowered the engine. It was too difficult - by careful lowering, we got to a point where it could come off without damaging anything.

With the engine & transaxle now on the board on the wheeled engine hoist, we disconnected the lifting gear. With the engine head removed, and therefore lower, we raised the vehicle further using a tall 'racing' trolley jack. This lifted the front of the car high enough to wheel the engine out. We then lowered the car back onto the axle stands. Note - in the interests of health & safety, we took care to do this without putting out body parts under the car whilst it was only on the jack!

With the engine & transaxle now out from under the car and having not had to purchase a vehicle lift, we removed 8 bolts & split the engine from the transaxle. This was a dry box & took a bit of wiggling. It helped to lift the heavier transaxle until the assembly was horizontal and wiggle & pull.

The now separate engine was now upended over an oil pan - despite having been drained of both, plenty of oil & coolant came pouring out. The engine was then turned upside down with the block face sitting on softwood, avoiding the two locating pins. The small sump was unbolted & pryed off with a screwdriver. The FIPG held fast here too, but it was easier than the timing cover. The sump proper was then unbolted. Note - there is a bolt below the oil filter. We had to remove the filter, unbolt the filter mounting bolt with an allen wrench and then remove the bolt below. The sump proper required a lot of effort to pry off.

With the sump off, it was now straightforward to disconnect piston #3 for inspection. There was no ridge to ream. The piston was removed & the rings were found to be all present, though there was quite a lot of scoring on the piston surface.

We then turned out attention to the stuck half CV joints in the transaxle. The engine side half joint was removed by repeatedly prying with the crowbar. This was not easy or straightforward at all - from the design I don't know whether there is an SST puller type tool for this - but it didn't go very well. The transaxle side half CV joint was removed by tipping the transaxle onto it's side (despite having been drained, more transmission fluid leaked) and pulling on it with the engine hoist & a soft strap. Unfortunately we couldn't come up with a better way of doing this - if anyone has managed to get these out I would be very interested to know how! Our solution was to apply steady, firm pressure and then pry sideways with the bar to get it to pop out.

So, that's Swamp - 1. Currently with the engine out and a bit of a debate about what to do next. I intend to fit a second hand engine... I don't have one yet but hopefully within the next few weeks I will be able to source one & swap it in. Despite labeling this along the way - I suspect re-assembly will be something of a challenge.

A few more points of interest...

This engine was consuming appx 5l of oil every 10,000 miles which is rather high.
The water pump removed was immaculate & is the original.
I did a boil up test on the thermostat, which opened at 89 degrees - and again is the original.
The drive belt has minor cracking (I was going to replace it anyway as it was off) but remained acceptable and again is the original.

You can see some of the LPG conversion kit in the pictures - I haven't described it above as the removal is relatively straightforward as it is all at the top. The LPG parts simply came off before those they were attached to. A small amount of propane in the fuel line was vented to atmosphere.

Previously, this car has had a replacement exhaust backbox, nearside front wheel bearing and rear coil springs - all DIY jobs. The LPG conversion is also DIY.

For now, transport is provided by Swamp - 2, another 2005 Gen 2 Prius, but with 103,000 miles on the clock. Hopefully this one will last as long as the first, but I'd like to get the first one repaired and working again. Thanks for reading & I hope that was of some interest - I've found a lot of other peoples descriptions of jobs they have done very helpful over the years, so here is a little bit about mine.

Matt

 

Hi EKIM,
Unfortunately I couldn't see a way to get the pan off with the engine attached to the transmission - better men might be able to do it but it looked like it was bolted on by robot & there was no access to do it without separating the engine from the transmission. I wasn't convinced I could do that without dropping the engine & transmission out of the car. The job is still going on, now with a re-built engine (post with lots of pictures to follow) but not quite all back together yet.

 

Hi Patrick,
The #3 bore in the block was in good condition, I chose not to re-use it based the replacement I bought - a nice long post below. I think that if the piston was replaced & re-ringed, the block would be fine to re-use, but I haven't done that.

Thanks

Matt

 

Dear Prius – Chat users, time for an update…
As you may have seen from my other posts, I’m currently having some problems with ATF leaks, but a lot of progress has been made, so here we go…

With the engine out & disassembled, eBay was perused for a replacement unit. Unfortunately the cost of two valves, a replacement piston, rings & new valve seals was prohibitively expensive. A second engine came from Coventry. This was sold as a ‘broken’ unit – the small sump had been removed to repair another vehicle & the pan had been damaged in the process – the pan was scored where the small sump attaches & I wasn’t able to bring it back to flat with the file. The unit did have good compression & turned over okay. Prior to starting work a blow – by test was done & was good on all 4 cylinders. As the engine had no small sump, the compressed air which was passing the rings was being vented via the pan & we could hear the flow of air quite clearly. All 4 cylinders were acceptable and fairly even.

To make 1 good engine out of two broken ones it was necessary to attach the original pan & small sump to the replacement engine. Unfortunately this requires the timing cover off & a reasonable amount of disassembly. Both the pan to block, timing cover to engine & small sump to pan are FIPG. The re-used parts were cleaned thoroughly with de-greaser prior to assembly. Winns FIPG was used throughout. There are two ‘O’ rings within the pan which were replaced with generics. The rocker cover of the replacement engine was also removed & the valve clearances were checked. All were well within spec. There was evidence that this job had been carried out previously.

During assembly the timing cover was fitted last. A large amount of FIPG is required. There are areas, for example around the water pump where an internal seal of FIPG is required – the old one had to be carefully scraped off, cleaned & a new seal applied.

With the engine completely assembled, a new water pump, oil filter & drive belt were fitted. The coolant pump, pulley drive wheel & belt assembly were completely assembled & tensioned with the engine on the bench. The flywheel / input damper from the original engine was then transferred to the replacement. This was relatively straightforward to remove and transfer. A clutch alignment tool and an amount of wiggling & common sense was all that was needed to line it up. It was quite clearly central or not. Care was taken to mark the alignment of the input damper with the flywheel (permanent marker pen) and replace it in the same orientation. There was very little evidence of any wear. The spark plugs were also replaced with NGC LPG – 1s. this was for three reasons… the original plugs were quite messy after the head gasket failure, the plugs which arrived with the second engine didn’t look very good either & the car is an LPG conversion, so we went with the NGK recommendation.

On the transmission side, both driveshaft oil seals were removed & replaced. These came out easily by very gentle prying with the crowbar. New seals were tapped gently into position with a small drift (I didn’t have the SST or a suitable socket). There are some problems here – both seals were tapped all the way down & the long side is still leaking fluid. I am told that this is wrong & the seals should be flush with the transmission, with the lips sticking out. I am going to have another go & see if this deals with the leak.
Moving on to the driveshafts, both separated CV joints were refilled with moly grease & new boot clamps were fitted. It is important to set the driveshafts to the specified length at this point – we forgot to do this & had to sort it out later, most definitely doing things the hard way.

The engine & transmission were then re-coupled. With an assistant the transmission was supported by the engine hoist. (It is significantly heavier than the engine). The engine was then placed on a dolly underneath the hoist & the two were manipulated together. Quite a lot of wiggling allowed both the engine & transmission to be worked together without using the bolts. The splined shaft was deliberately left dry as the input damper is a dry box & we didn’t fancy introducing any oil – I don’t know whether this is correct or not.

With the engine & transmission together, the assembly was dollied under the car & lifted up into position. With the assembly part raised, the transducer was re-attached to the back of the transmission & some electrical connects which are inaccessible with the transmission bolted in re-attached. This was awkward as the engine & transmission need to go in at an angle & then be ‘rolled’ into place, however we were unwilling to remove the sub-frame and did not have access to a vehicle lift. The radiators were pulled forwards & the fans removed to improve clearances.

With the engine in places hoses & connecters were re-attached & fluids filled. Unfortunately the engine coolant leaked, both from the small pipe on the front of the engine block & from the radiator. The small pipe leak was solved with a new gasket, unfortunately the radiator was now cracked (possibly damaged on engine removal / installation) and a pattern part was fitted. Due to corrosion this required a lot of drilling out. Both of the lower support brackets were replaced with new, the tops were re-used originals. This has now been filled & run up to temperature – all seems to be working okay. Bleeding up went fine – the funnel kit recommended on here worked very well for me, thanks for the tip!

Moving on to the power electronics side, one of the lower coolant hoses was replaced as it had perished. Re-fitting the inverter was straightforward. The coolant we re-filled with the bleed valve open. A little tip, setting the car to on but not ready (i.e. press the power button twice without pressing the brake pedal) makes the hybrid coolant pump run but does not attempt to start the engine. This allows you to bleed up the power electronic coolant without heating up the power electronics due to air locks. Opening the small bleed valve is essential. We found that the coolant pump with the bleed valve open would rapidly draw coolant into the system. Each time the reservoir emptied we switched the car off to re-fill. We then ran the car in this way for 20 minutes with the coolant circulating (visible flow in the reservoir) topping up as required. Air bubbles continued for some time. We could also hear the air in the hybrid coolant pump. The sound progressively changed as the air was removed. Eventually the bleed valve was closed as it was leaking coolant from around the thread & no further bubbles were leaving the system this way.

The engine & transmission were then filled with oil. The engine was all good news – no leaks. The transmission on the other hand had a tiny weep of ATF. This was leaking from the long side & remains an unresolved problem. The car also would not start – a big red triangle of death. We were not able to identify the problem with the scan gauge and had to buy the recommended techstream interface – again, thanks PriusChat for the tip! This revealed a wealth of error codes, the most important being the HV safety lockout. This was cleared by investigating the HV safety plug & the inverter covers – we didn’t find anything wrong but the act of taking them out & putting them back in again cleared the problem & the car started. Unfortunately, this immediately resulted in a petrol leak. The car was stopped & the fuel rail installed ‘better.’ It seems that it is very important to wet the injector seals in fuel & take care to fully rotate them on installation. With this problem cleared, the car started & was allowed to run up. The engine coolant produced quite a few bubbles in the funnel which were supplied with additional coolant. The car was run up to temperature (fan cut in at ~90 degrees) on petrol & LPG.

That now brings us up to date. There are some remaining problems – the driveshaft oil seals to install better to clear the ATF leak, the outside temperature sensor was heavily corroded & whilst the sensor has been replaced, the connector is damaged & doesn’t work, I have not been able to source the correct replacement. There is still quite a lot of re-assembly required, the centre engine support is off along with the front bumper & various covers. Hopefully the driveshaft ATF leak will be resolved & the job will carry on.
A few observations…

The HV battery with the safety plug removed has plenty of power in it to start the car after 4 months of standing. The LV battery was maintained throughout by an optimate charger.

Both front fog lights were severely corroded & have been replaced with pattern parts – the reflectors had corroded & cracked. They were removed by smashing out with a hammer, it was not possible to undo them due to the severe corrosion.

Problems are very difficult to diagnose without the techstream – the aftermarket interface is excellent though & highly recommended. Trying to guess what the matter was with only the scan gauge was nigh on impossible.

Thanks for reading.
Matt

 

Dear Prius chat users,
Some more progress... Following advice, the drivers side driveshaft oil seal was gently slipped out, inspected & re-seated flush with the transmission, the drive shaft re-installed & lo & behold, the AFT leak has stopped. With the transmission refilled & no longer leaking, the engine was run up with the car on axle stands & both driveshafts allowed to rotate with the wheels off the ground... still no leaks! Having run the car up to temperature & allowed it to cool, around 1/3rd of the expansion tank of coolant was drawn into the cooling system & topped up, again, no leaks when running at 90 degrees so all good so far.

The front end of the car was then largely re-assembled with the central engine support back on & the front bumper re-fitted, along with the bonnet & most of the top of the car. The plan now is to finish re-assembly & then go for a test drive... hopefully this job is coming to a close.

 

80,000 miles on LPG, a mix of 70mph motorway cruising & 30 - 60 mph B roads, no valve adjustments - they were slightly tight when the rocker cover came off, but only ever so slightly out of spec.

Cheers

Matt

 

Thanks Chap - I hadn't realised but now you point it out - that's really interesting.