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Leaky Lemon


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Hi all,

First post !! May be a bit long but I'll try and make it as entertaining as possible!

My long endured desire to own a Lexus momentarily outweighed everything I know about buying a used motor and I've gone and bought a bit of a lemon!

It's a '94 GS300 with about 170,000 on the clock, which would be fine I suppose if it had been maintained properly (at all!) but it's got no service history and appears to have been maintained by an idiot. The oily muck on the bottom of the engine should have warned me off somewhat but the gentleman selling assured me it had just had an oil leak fixed (rocker covers he said) and it was advertised as 'perfect' so I took a chance... anyway, long story short when I got it home I found it leaking oil and water from all over the place. (Water pump, dip-stick hole, distributor, LPG regulator and from somewhere behind the timing belt)

Here's what I've done so far:

  • Replaced water pump gasket, easy job, bloody hard to get just just a gasket, made one myself in the end. Do you believe someone had actually refitted the water pump without fitting any gasket at all, how they expected that not to leak escapes me. Although he did the bolts up VERY tight, guess he thought that would be as good as a gasket.
  • Repaired water leak on LPG regulator, well, when I say repaired I encased the water connections with epoxy leak-fix, not ideal but will do for now and looking under the car while idling is longer reminiscent of Niagara Falls. On to the oil leaks...
  • Replaced cam shaft oil seals
  • Replaced dizzy o-ring and cap seal
  • Replaced dip-stick o-ring
  • Repaired various vacuum and gas lines (well, cut off the frayed ends and made good)
  • This is a good one... - Replaced crank pully bolt, unbelievably someone had prevously undone it with a an air chisel, and then NOT TIGHTENED IT BACK UP AT ALL! I was actually able to remove the bolt with just my fingers! Which as lucky as it had been mangled to point of not being able to get a socket on. The pulley must have been very loose (actually floppy) as it has scuffed up the lower timing belt cover! Counting my blessings on that one.
  • Replaced rotor arm which was eroded by about 2mm. Still need to replace the cap, spark plugs and some of the HT leads which have Ford written on them.
  • All this would be fine if I'd actually managed to fix the oil leak, it still seems to leaking oil from around the dip-stick area AND the dizzy. I'm getting oil pooling on top of the water pump and the dizzy heat shield (Yes, I realise that swapping out a rotor arm will not help with an oil leak!)

The engine seems to run fine, nice and strong, sounds ok, not burning any oil, but still throwing its oil out of every possible seal.

The poorly refitted crank pully has let me believe that crank front oil seal may have been replaced, possible very badly. Could this cause oil pressure problems? Can the oil-pressure relief valve actually fail?

I've ordered a crank-shaft front oil seal and will fit that when it turns up, probably this weekend so that'll be me pulling my engine apart on my birthday!

If anyone can suggest anything else I should look at I'd appreciate it.

All comments, suggestions and LOLs are welcomed.

Kindest regards,


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Only time i see oil leaking out from many parts of the engine is when the rings had gone, letting compression past. Would suggest a comprssion test.



That occured to me too, but I get no smoke when starting or driving. I'll pull out the plugs and do a cylinder compression test tonight.

Oil being forced though the dipstick hole does seem to indicate high sump pressure to me though.

Any 2jz gurus reading this??

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Can't think of anything specific but would agree that there would appear to be positive pressure in the crank case. If the compression test is fine, then I would recheck all of the vacuum pipes, as you could have a blocked breather somewhere.

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Well, I took the car to a friends garage yesterday so I could put it up on the ramps and have a better look round/under it. As well as leaking oil from the front and sides of the engine, it's also leaking from the back so it looks like the rear oil seal is gone too.

As well as the oil leak problem it's developed a rattle from the front left wheel when driving over bumps, some gentle prying with a crow bar has revealed that the some of the rubber subframe mounts have perished.

With a heavy heart I took the car home and removed the throttle body so I could pull the plugs and do a compression test and discovered that the plug-gulley (if that's the right term) has about an inch and half of oil in it! Some of the bolts holding the throttle body to the manifold/plenum have not been tightened and many of the rocker-cover bolts were also loose!

Oil, oil everywhere! You may think there's a lot of oil floating about in the Gulf of Mexico right now but that's nothing compared to the unnatural disaster under the bonnet of my GS.

I cant pull the plugs yet until i've cleared all the oil out or it will just run down the plug hole, so I'm off to do that now.. Great way to spend a 40th birthday!


Oil now cleaned away, here are my compression test results. Comments please!

Cyl psi

1 175

2 163

3 165

4 155 (176 with cap-full of oil dropped into the cylinder)

5 165

6 175

The Lexus workshop manual specifies 156psi minimum so I'm only just outside that on no.4. The motor has just over 170k on it so I'm not surprised the rings are a little worn. What I want to know is are they too worn and the cause of my oil pressure problems?

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What do you mean "oil pressure problems".

Well, it might not be an oil pressure issue, I don't have an oil pressure gauge to confirm what the oil pressure actually is...

It's leaking oil from just about everywhere its possible to leak oil from is what made me suspect high oil pressure.

Initially I thought it was due to worn oil seals and o-rings as mostly it seemed to be leaking from the front of the engine, the distributor port and where the dipstick goes into the sump.

So I fitted new o-rings to the distributor and the dipstick and changed the camshaft oil seals. This didn't help, so I then suspected the leaks may be due to high oil pressure caused by either buggered oil pressure relief valve or worn rings, so I dug out my compression gauge and plug spanner and it was then that I discovered the oil-slick pictured above.

I've cleaned all that up now (resorting to a straw to pull the last bits oil from the plug holes before removing the plugs) and fitted new rocker-cover gaskets. The low cylinder compression on No.4 is certainly due to slightly worn rings on that cylinder but as it's only just outside what Lexus say is acceptable so I think it's not the cause of the problem. But I would some opinions on the compression test results.

I've not road tested the car yet (since changing rocker cover gaskets) due to waiting on new plugs from eBay.

I also want to change the front crank oil-seal for which the Toyota stealer robbed me of nearly £20. I'll do that tomorrow.

I have two questions really:

* Are my compression test results 'acceptable' considering age and mileage

* Considering the incredibly poor maintenance the engine seems to have had (evidenced by the loose crank pulley bolt and noumber of nissing nuts and bolts etc), can an incorrectly fitted front oil seal cause the numerous leaks due to the oil pressure relief hole being blocked (oil seal pushed too far in)?

I'll know more after tomorrow, I'm just after some opinions and ideas.

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Dude, can you cut your losses and bin it? You could spend a fortune an it may never be right, unless you're planning to keep it for a long time.

Yeah, this is the thing. I probably should bin it, but I payed top dollar for it, its got a good LPG kit on it and I don't quit easy! :crying: So far I've not spent that much on parts, but I have spent quite long time outside working on it. I'm learning a lot. I don't plan on getting rid until it's payed for itself in fuel saving (due to lpg, I'll be about £1k a year better off)

Also binning it would be like admitting to the missus that she was right, and I can't have that!!! :whistling:

The cut-off point will be if the engine needs major work, while I don't have to pull the block out (which i can't do as I don't have a garage) I'll keep going! (sucker for punishment maybe..)

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You seem determined to fix it, great attitude! Oil pressure on its own is unlikely to cause such oil leaks. The seals that you are replacing don't get oil pump pressure but they do get crank case pressure and it sounds like that to me.

I don't know what pressure the relief valve is set to but I am pretty sure that during normal driving, with a warm engine, the pressure relief valve will not be asked to to operate very often. Probably only if you rev it hard. If you are able to measure it you should get about 50 to 60psi at 3000 rpm (gauges vary a bit) and 25 to 30 at idle.

I had a Toyota that developed high crankcase compression due to a failing head gasket. The cylinder pressure was blowing into the crankcase via an oil drainage passageway. This didn't cause the engine to leak oil but it built up oil in the crankcase ventilation system and was dumped into the intake on overrun - masses of blue smoke out the exhaust!!! It doesn't sound as though that's happening to you but there's more than one way of getting high crankcase pressure. If you have a blocked PCV valve this could cause pressure to build in the crankcase. There is one fitted into the top left hand cam cover near the rear (mine is Mk2) I don't know if there's another. See if it's flowing air (they usually rattle if they are free).

You have no evidence of bad rings from exhaust smoke or oil use and your compression pressures are within spec. (Compression test gauges are also a bit variable)

All the seals tend to go hard with age - when I did the full top end overhaul on my Toyota (Camry 3.0l V6) I replaced one exhaust valve because it was burned where that head gasket had been leaking, all the others were in top condition - the stems had no measurable wear at 140,000 miles - I took them to an engineering shop for checking and they were amazed. One thing I didn't do was replace the water pump - big mistake! The bearing packed up 50,000 miles later and shredded the cam belt.


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Hard to say if the compression test on 4 is OK. It is not a terrible reading so probably ok. I had a cracked ring on my old V8 Rover Vitesse and you could see the gasses blowing back through the oil filler cap if you removed it. Unless it is something like that, you are probably ok. On the same Rover, I also had a blocked breather at one point and that forced oil out from the push rod cover in the V of the engine. This would seem to sound more like what you are getting. I've not tried it on my GS, but can you run the car with the oil cap off and see if the leaking subsides at all?

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  • 1 month later...

Well, it took me several weeks (only being able to work on it for an hour or two every few days plus a few afternoons) but I've changed the head-gasket and all now seems well.

To be honest it was a nightmare of a job, I've done several HGs before but so many of the bolts on this engine are inaccessible and theres just so much stuff to take off (LPG), it was definately the most difficult.

The oil leak issues are now resolved barring an occasional drop from the rear crank oil seal.

Next job is the front lower bushes, God help me!

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Well, it took me several weeks (only being able to work on it for an hour or two every few days plus a few afternoons) but I've changed the head-gasket and all now seems well.

To be honest it was a nightmare of a job, I've done several HGs before but so many of the bolts on this engine are inaccessible and theres just so much stuff to take off (LPG), it was definately the most difficult.

The oil leak issues are now resolved barring an occasional drop from the rear crank oil seal.

Next job is the front lower bushes, God help me!

So it WAS the same cause as my old Toyata Camry - amazing. It is a tough job changing a head gasket on a big engine with complex control systems. Did you find the weak pont in the gasket? Be thankful you only had one head and two cams rather than the two heads and two cams on my Camry :winky:


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