Compression tested my engine!!!!!

[simers]

@ stupink
If all comes to all I think the engine is going to have to be rebuilt but no way in hell am I paying for it as its not my mistake

[stupink]

As above the heat is far from insignificant, it *IS* the reason compression figures are higher.

diesel fired into cylinders, nothing happens, compressed, bang, it starts..  no spark plugs, and glow plugs (if on) are hot all the time so why not combust when the diesels injected.

[MattPerformance]

As was mentioned early in the thread, the numbers in isolation may be misleading if we don't know the conditions of the test (throttle open or not, fuel disconnected, number of cranks, engine hot or cold...).  There is also the matter of gauge calibration.  My gauge is good but old so I cannot say how the readings I see might compare to another gauge but fluctuations over the cylinders will be a good indication at least.  But as said I expect to see upwards of 190psi (my and Jason's track car with low comp pistons even makes 175psi)

In my experience (25+ engines) oval bore is a MYTH.  I have never yet seen an engine with an oval bore!!  I've scrapped a few blocks due to piston related bore damage or corrosion due to head gasket failure but never an oval bore.  Ironically the last but one block I scrapped was because it had been overbored and the piston to bore clearance was too great!!  The quality of the piston rings being used is a massive factor in the effectiveness of a rebuild in my experience.  I have built at least two two previously rebuilt engines that suffered poor running due to compression issues having been fitted with low quality rings.  My advice would be only use genuine Toyota parts (I've seen a couple of head gasket failures too within 12 months where cheap factor gaskets have been used) but that obviously adds a lot of cost compared to the cheaper alternatives (but worth every penny in my opinion).  I would add that a genuine Toyota head gasket is extremely resilient to minor overheats so one brief foray into the red shouldn't cause it to fail normally, but a cheap factor one will probably fair less well.  See if you can find out what parts were used and also if the head bots were replaced.

As has also been mentioned, the valve seating will have an impact on compression test readings (as can valve timing and shim adjustment!!) so finding out what work was done here is also important.

If it's still burning oil the problem will almost certainly be that the pistons were not properly cleaned, especially the oil control ring recess holes.  If these holes stay blocked then the oil consumption will remain immediately after the rebuild.

Unfortunately there is only one course of action: get the engine stripped and repaired properly. (getting another engine is an option but it won't determine what went wrong)

How you cover the cost of that new repair is another matter...

[normanh]

pv = nrt

My last word on the matter.

[stupink]

pv = nrt

My last word on the matter.

 m https://www.youtube.com/watch?v=rum-lbJowBM m

And my last..

[Jon_G]

pv = nrt

My last word on the matter.

Yes, the formula is appropriate to the situation, but nevertheless not particularly helpful due to the uncertainty of the gas temperature... the adiabatic process will raise the gas temperature, but this is mitigated by heat soak into the engine block and head. It could be modelled, but would defy simple calculation.

But hopefully now it is clear that compression reading are not simply atmospheric pressure x compression ratio!

Better to compare your test readings to those obtained from a known good engine, using similar test conditions, as has already been suggested.

[simers]

pv = nrt

My last word on the matter.

Yes, the formula is appropriate to the situation, but nevertheless not particularly helpful due to the uncertainty of the gas temperature... the adiabatic process will raise the gas temperature, but this is mitigated by heat soak into the engine block and head. It could be modelled, but would defy simple calculation.

But hopefully now it is clear that compression reading are not simply atmospheric pressure x compression ratio!

Better to compare your test readings to those obtained from a known good engine, using similar test conditions, as has already been suggested.

The problem is there are no mk3 mr2's around here so I really have nothing to base it against...
@ Matt
The full rebuild set including head bolts came from a reputable engineering company... So I doubt they would be giving out cheap tat if ya get me.. Like the full rebuild kit cost me the best part of €600 but that also covered the crank work which was approx €100
What should a full kit from Toyota cost as I never actually priced it there but judging by the cost of a rad over here @ €575+ vat I'd say it would have been a lot more expensive than what I did pay...
The clown that rebuilt my engine said he will have a look and see what is wrong but that means the head coming off again so another gasket etc just to keep things proper and all that jazz...
As for the rad bursting I no the head gasket is ok as she is not losing any water at all so I'd say it down to a poor job rebuilding it...

[AmeR]

According to Toyota, the Compression Pressure of a stock 1ZZ as found in these cars should be:
1,270kPa / 13.0kgf/cm(sq) / 184psi

Minimum pressure of:
1,000kPa / 10.2kgf/cm(sq) / 145psi

With a difference between each cylinder of 100kPa / 1.0kgf/cm(sq) / 15psi or less

Being that its their engine and I'd imagine they've spent a tad more on research, development and construction of the engines than I'm likely to earn in a lifetime, can we put the pi$$ing contest to bed and afford the OP some advice?

The official line for Toyota is:
1. Warm up and stop the engine
2. Remove ignition coils
3. Remove spark plugs
4. Inspect compression (insert gauge, fully open throttle)
Hint: always use a fully charged battery to obtain engine speed of 250rpm or more

Is that the procedure you followed?

[simers]

According to Toyota, the Compression Pressure of a stock 1ZZ as found in these cars should be:
1,270kPa / 13.0kgf/cm(sq) / 184psi

Minimum pressure of:
1,000kPa / 10.2kgf/cm(sq) / 145psi

With a difference between each cylinder of 100kPa / 1.0kgf/cm(sq) / 15psi or less

Being that its their engine and I'd imagine they've spent a tad more on research, development and construction of the engines than I'm likely to earn in a lifetime, can we put the pi$$ing contest to bed and afford the OP some advice?

The official line for Toyota is:
1. Warm up and stop the engine
2. Remove ignition coils
3. Remove spark plugs
4. Inspect compression (insert gauge, fully open throttle)
Hint: always use a fully charged battery to obtain engine speed of 250rpm or more

Is that the procedure you followed?

Sounds about right as to what I did but didn't open throttle at all... Bearing in mind I'd never done a compression test before so I think I may have made a bit of a mistake on my part... As regards the test that is....Also the engine wasn't fully up to normal temp... Might just try it again tomorrow to see if it makes any difference but the fact it's low on three cylinders would opening throttle etc make much of a difference???
Also AmeR thanks for that bit of info as I've said before I've never really done a compression test before and now I no how to do one properly... Appreciated  s:) s:)

[Anonymous]

Well im glad that contest is over now.
simers you say 500 for a full kit. Can you give more details as I would expect a normal rebuild in parts to be more, but then I guess matt would no the exact price.

[simers]

Well I'm glad that contest is over now.
simers you say 500 for a full kit. Can you give more details as I would expect a normal rebuild in parts to be more, but then I guess matt would no the exact price.

No problem on the run down of parts mate... Full head set including head bolts valve stem seals also included... New rings thrust washers(prob pronounced wrong) big end bearings and small ends.. Think that's everything I bought new... Reused water pump and oil pump at the time as I didn't have the money for new ones but they were both perfect and oil pump was fully cleaned out too to make sure no filings from crank damage ended up getting stuck in there...

[stupink]

I'll be honest im a bit sadened this has been called a "contest" and "pissing contest" and suggestins we are not being helpful.

I put my time and effort into forums and cars in general and try to be as helpful as i can.

if you check the first reply its mine, i stated the conditinons for a good compression test, including the throttle should be open, and that 150 was too low *if that had been done*.. the op appears to have ignored that, and i then tried to explain why someone else who claimed those figures alright was not correct so the op was not confused/mislead. ensuring the thread was factual not full of pub talk and speculation.

If the throttle is shut ie a restrictor, then yes you will get low compressino pressure readings, if air can't get into the cylinder it can't be compressed.

this could potentially also explain the variety between cylinders, i would not worry too much about 20psi difference on a cold engine tested incorrectly.. forget the figures entirely.. throw them in the bin.

go warm up the engine properly, and test it properly as above.. then repost accurate figures for all cylinders so we can advise  s:) s:)

[simers]

I'll be honest I'm a bit sadened this has been called a "contest" and "**** contest" and suggestins we are not being helpful.

I put my time and effort into forums and cars in general and try to be as helpful as i can.

if you check the first reply its mine, i stated the conditinons for a good compression test, including the throttle should be open, and that 150 was too low *if that had been done*.. the op appears to have ignored that, and i then tried to explain why someone else who claimed those figures alright was not correct so the op was not confused/mislead. ensuring the thread was factual not full of pub talk and speculation.

If the throttle is shut ie a restrictor, then yes you will get low compressino pressure readings, if air can't get into the cylinder it can't be compressed.

this could potentially also explain the variety between cylinders, i would not worry too much about 20psi difference on a cold engine tested incorrectly.. forget the figures entirely.. throw them in the bin.

go warm up the engine properly, and test it properly as above.. then repost accurate figures for all cylinders so we can advise  s:) s:)

Now I never said it was a contest or whatever your first line of this post said mate... I'm very appreciative of you original post as it was very helpful.. I am unable to do compression test today unfortunately due to the garage where I got it done being closed.. i.e loan of compression tester... Will post more accurate ones on the morning now I no how to do it properly...
Once again sorry if I caused any offence or disregarded your input but all very valuable to a guy who nos nothing about the internals of an engine or how to rebuild one never mind take one apart.. Well that's the easy bit  s:lol: :lol: s:lol:

[Wabbitkilla]

I don't think anyone needs to get upset chums, this thread has gone form good information to better information drawing on the Toyota specs. Simers definitely has some solid figure to look for now Anthe way to measure accurately. I for one want to see his eventual results and find out what the root. cause of h problem is.

To guess, I would say the engine has been rebuilt without checking the bore consistency and honing was necessary ... but it is only a guess at the moment.

Whatever happens I hope Simers can get a fix and be happy with the car again.  s:D s:D

[simers]

I don't think anyone needs to get upset chums, this thread has gone form good information to better information drawing on the Toyota specs. Simers definitely has some solid figure to look for now Anthe way to measure accurately. I for one want to see his eventual results and find out what the root. cause of h problem is.

To guess, I would say the engine has been rebuilt without checking the bore consistency and honing was necessary ... but it is only a guess at the moment.

Whatever happens I hope Simers can get a fix and be happy with the car again.  s:D s:D

I hope I can too mate as being honest I feel like getting rid of her at the minute and cutting my losses... The car is 01 and standing me 4k at the minute and now more than likely have to rebuild the engine again at possibly my own expense...
I would be lucky to get 2k for it over here which works out at about 1600pound sterling which is shocking money you no....


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[Anonymous]

http://www.mr2roc.org/phpBB3/viewtopic.php?f=11&t=32144&hilit=

The figures and good info were in this link I posted on the 1st page,did you even bother to look at this?

[simers]

http://www.mr2roc.org/phpBB3/viewtopic.php?f=11&t=32144&hilit=

The figures and good info were in this link I posted on the 1st page,did you even bother to look at this?

I don't have access to a laptop mate and the links don't come up on my phone... As said before apologies if I made anyone's feedback invaluable as every little bit helps...


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[stupink]

seems to have gone quiet. did you get those new figures or get your problem sorted? always nice to hear back the end result of posts.

[simers]

I haven't done anything with the engine lately as I've been using it as my daily while waiting on my new car (Mitsibishi evo 1) it's going back in garage again this week to be retested

[stupink]

ahhh.. attack of winter-itus... i have that also and have done nothing for weeks  s:( s:(

[simers]

ahhh.. attack of winter-itus... i have that also and have done nothing for weeks  s:( s:(

Must be a case of it and a bad one because I scrapped my other winter project and now I'm putting the 2 on the long finger