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compression test on a car

Discussion in 'The Pub' at netrider.net.au started by Zbike, May 17, 2007.

  1. I think this belongs in here rather than off topic but move if u think other wise plz

    When doing a compression test on a car should i give the car gass (step on the throttle or not)

    whats a good reading for a diesile engine in PSI terms. My GPX is reading 110 and running fine
    the GPX manual saiz it should be 150-180 psi
    while generic manuals say most thing over 100 should run and 130 is great
    Anyways i got all the tools im not sure if im taking the readings wrong or the manual is over zeolouse, as i dont wana make the same mistake takin the reading for the car

    Its a desile ute with about 300,000 kms on it.
    automatic 84 hilux
    looks in very good nick for its age and registered but unkown if/when it was rebuilt last

    anyways im thinkin of bying it but dont wan be hit up for rebuild costs i could probaly do top end myself but i would take me a good part of a week to do. I wouldnt attemp a gearbox/bottom end rebuild

    yes i will try to get my car mechanicly minded mate to come with me

    R u still with me cheers
  2. A diesel engine should read much higher than a petrol - at a guess something like a Hilux is probably going to be around 3-400psi. 300k is getting on a bit - biggest problem with diesels is not so much with the engine but with the fuel injection system (which on an '83 would be mechanical). Fuel injection is way more complicated with a diesel due to the higher pressures and fixing it requires a specialist diesel mechanic who generally don't work cheap.
  3. Not sure how you do a comp test on a diesel as there is no plug hole to use. Diesels have comp ratios of 20 -25/1 which is about double that of most petrol engines so if you can do a test it should be about double the PSI.
    2 Test are usually done. Dry and wet but usually with throttle closed.
  4. My liking to this particular one was that its an 84 model which is the last to have mechanical/carb 85 onwards it would seem have fuel injection however this may only apply to petrol not diesle engines i suppose i will know for sure tonight.
    Plus this one inparticular is an automatic :shock:
    link to Hilx ebay page
    apparently current owner bough it from a dealership $3.5k (sounds like too much)

    No plug hole erm ok. :) that rite deisle explode from high presure not spark.
    Im hoping there is something to screw a gauge into.

    so 350-400 Psi would probaly indicate its had a rebuild
  5. No spark plug but there is a glowplug. Not sure how you go about compression testing a diesel - but I do know it can be done. Also even mechanical fuel injection is not something the average home mechanic can even hope to work on. With a diesel fuel is injected directly into the cylinder at extremely high pressure - there's no compression stroke and certainly no carb. Even mechanical injection on a petrol engined car can be a nightmare to fix. My brother actually has a Hilux about that age - main problems he's had with that have been the rear axle moving out of alignment (beware any "clunks" coming from the rear) and the radiator corroding out.
  6. Am I missing something jd? A diesel is a 4-stroke compression ignition engine which most certainly does have a compression stroke. Ok, there are 2-stroke diesels, but they tend to be 50,000HP and powering supertankers.
  7. JD: Not all diesels have glow plugs. (Although this engine does)
    Inci: The good 'ol faithful GM's are 2stroke. Love that sound!
  8. Yep. What I meant was that there's no compression of the fuel, just the air - so you don't have a carb feeding and air/fuel mix into the engine.
  9. $3k won't buy you a lot of Hilux...

    But they are out there.

    Here's one with the engine swapped out for a 4.2L V8 dual fuel [pet/LPG] ... it's the old 253 long-stroker so it's more for torque than power and a much safer purchase from a drive-train perspective than a 308 or 350 conversion, etc.

    I've called the guy - he didn't do the conversion and he doesn't know how many k's the new engine has done. It does have some surface rust on the body and there's a hole in the floor of the cabin which should be fixed with a bit of plate.

    4wd works & you can fit 2 bikes in easy. Rego til November.

    I'm shopping for a cheap truck too :) I miss my 99 Hilux like crazy, so I'm just after something to thrash around the bush, pickup loads of firewood and carry the odd crashed bike home for mates/me etc.

    If you're looking for something that cheap and old, you should also consider old GQ patrols. They're harder to find in a tray-back/ute, but a lot more of them still have the original motor running than Hiluxes of the same age/k's, and the diffs and drivetrains in them are a lot tougher too.

    There's a dude on Ebay selling an '86 Single cab Hilux which needs some work to the head. Apparently runs ok-ish, just with a bit of noise: bidding is at about $1200 with no reserve at the moment - it's in Parramatta too.

    It's also 4wd, but no lift. Some chunky tyres and the body looks pretty straight. If you could score it for under $2.5k it'd probably be worth paying for an overhaul on it.

    ... there's also a dealer in Canterbury on Parramatta Rd with a blue single cab for sale, with a crap-load of K's on it, but original bits and seems mostly looked after. Asking $2999 I think.

    Hmmm, can't find it. BUT you could offer this guy $3k and see what he says ^_^
  10. I went and had a look the the hilux seem in decent nic minimal rust for its age.

    However the motor seems to have a dull sounding knoc that is intermitand as its there for a few secounds and then isnt.

    Now the guy said he spent 3500 buyin it and 700 on tyres and bits an pieces i can score it for around 2000-2500. he does have a twin cab later model ute and a few other toys.

    My sucpesion is the knockin is somthing gone foul and its expensive to fix thats y he doesnt drive that ute and bough another one.

    thanks kutlu actualy the guy in parramata is my next stop tomorw or saterday since a head gasket in a comparativly easy repair job,

    4.2 litre V8 is nice but is probaly to big for my petrol budget not to mention im a bit of a nutter i wouldnt trust myself with a V8. However it is very tempting and looks like a sweet ride.
  11. These Diesel engines can cost a fortune to fix. I have checked over a few Hilux utes and the bill to get them in RWC condition has stoped the purchase from going ahead. The front drive shaft flogs out in them and a rebuild will set you back around $500 it is worse for vehicles with lift kits as it puts more strain on them. The 253 powered one would be better than a Diesel or petrol version and would be cheap to run on LPG. The 253 is a slug they don't call it a boat anchor for nothing. A Courier or Navara would be a better choice. If you do not need a 4X4 do not buy one as there is more to go wrong . Any of the jap utes of this vintage will be past there use by date. A 2 wd Hilux or Navara would be a better choice as you will be able to get a later model for the money. A compression test is not something you will be able to do without the right tools as a normal car type tester will not be able to do the job. If a Diesel engine blows blue smoke walk away. If it blows black smoke all the time it either has a leaking injector or a injector pump timing issue. A Diesel engine should blow a bit of black smoke on start up and then again if you put your foot into it. ( Diesel is always spelt with a capital D as a sign of respect for the inventor of the compression ignition engine Rudolf Diesel who drowned in 1913).
  12. i wouldnt be anywhere near the car, for fear of being hurt.
  13. I thought most Hiluxes ran a rigid front axle - and that it was only the grey import Surfs that used an independant front end?
  14. Nope, at least for the 4x4's my '99 was independant front-end.
    I think from mid 90's onwards they were.

    oz650r - that's why there are a few changed engines :) It's cheaper to replace than repair a diesel engine [if you can score a 2nd hand block from somewhere].
  15. That's what I thought - so given the OP was talking about an '83 model probably safe to assume that checking the drive shafts would be a waste of time ;).
  16. Yup, but a quick look to make sure the front axle's straight wouldn't be a bad idea :grin:
  17. Should be pretty noticeable from the steering feedback I'd imagine but yeah definately worth a look - as I mentioned earlier definately worth checking the back axle too.
  18. Yes this model lux will have a rigid front axle. By drive shaft I mean the shaft fron the transfer case to the front diff (prop shaft). It would be near imposible to bend either a front or rear axle housing. If one was bent there would not be much on the vehicle in useable condition. An old foreman of mine rebuilt an 86 Hilux Diesel for his nephew and it ended up costing $3500 calling in every last favour from our suppliers at the time and that was 10 years ago.
  19. If it's a 2wd ute, it will have independent front suspension by double wishbones and torsion bar springs.
    Teh diesels in these early cars are pathetically underpowered, and an auto one, at this age, will struggle to 100 km/h. My uncle had an 82 2.2 diesel manual 4wd new and he wanted it gone as soon as he bought it. Sadly for him, he had to hang on to it for 3 years.
    Personally, I'd factor in either a petrol engine swap soon after purchase, or just buy something else. The cost of a petrol swap would make me wait til a petrol ute came up. I like the 18R engine/5 speed in these utes, reasonable power, but indestructible engine.
    Frankly, the Toyotas are good vehciles, but are no more reliable than anything else at this age/mileage. I prefer teh larger utes in this age bracket, like XD Falcons, a WB Holden or even a late Valiant ute. All can be very cheap to run on gas, and tend to last a fair bit longer, and offer a LOT more comfort than a base model Jap ute.
    This all assumes a 2wd ute though, I'd never buy any 4wd with 300k kms, way to expensive to keep drivetrain repairs going on a 4wd at this age, regardless of manufacturer.
    Regards, Andrew.
  20. thank you for all year info.
    Ive pretty much being put off buyin this ute i have found a few similar ones that may be in better condition.
    Out in winsdor that ill will hope fully be checkin out 2morow