1HZ oil consumption

Submitted: Tuesday, Jan 04, 2022 at 15:19
ThreadID: 143047 Views:1255 Replies:5 FollowUps:7
Hi all. I am actually in South Africa but came across some old posts related to oil consumption for the 1HZ motor.

I have an 80 series with 370k km. At about 362k the engine overheated resulting in head damage. A new head was put in by Toyota. Since then I have gone through 3l of oil in 6000km. The engine had negligible oil consumption prior to this.

What are the likely causes? Without carrying out thorough diagnosis the garage suspects it might be rings and out of true cylinder bores but I wonder of they are trying to get away from responsibility. It's a 25 year old truck used for overlanding so there is a point at which I need to carefully reconsider what I spend on the truck.

Any inputs greatly appreciated.
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Reply By: Mikee5 - Tuesday, Jan 04, 2022 at 16:15

Tuesday, Jan 04, 2022 at 16:15
As a non-mechanic, I always understood you should never put a new head on an old block. You might have a scored bore or broken rings or simply the higher compression of the new head is sucking oil up past the rings.
AnswerID: 638996

Follow Up By: RMD - Tuesday, Jan 04, 2022 at 16:34

Tuesday, Jan 04, 2022 at 16:34
Mikee
Plenty of engine have had new heads and original blocks! No worries!
Oil does not suck up past the rings, It is deposited there by the crankshaft and sump oil mist and failed to be scraped off by the oil control rings, therefore now above the compression rings on upward stroke to be burnt.
Any higher compression, can't be more than designed, will cause greater blowby on ill performing compression rings and oil rings and force oil downward.
A scored bore can be seen when head is off!
Generally severe overheating damages rings and they become less outward pressure on cylinder wall. Less sealing of compression and less scraping oil off walls by oil rings.
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FollowupID: 917847

Reply By: RMD - Tuesday, Jan 04, 2022 at 16:22

Tuesday, Jan 04, 2022 at 16:22
Amol
If the engine is hot and running any oil burning from rings will be constant. If it is left to HOT idle for a while and then throttled up, ie, revs brought up suddenly and it smokes a bit and then settles down with minimal smoke in exhaust it may be the new head does not have proper valve stem seals, or they are not sealing, or were poorly fitted with the new head.

Any ring damage or "out of true bores" if that happens, can be detected by a compression test. If it was well cooked then the rings may be the issue, ie loss of radial tension on cylinder walls.
New rings at minimum if that is the problem.
AnswerID: 638997

Reply By: Amol K - Tuesday, Jan 04, 2022 at 16:41

Tuesday, Jan 04, 2022 at 16:41
Thanks.

So new stem seals were installed with the head and I am hoping that is the cause of the problem.

However rings and a out of true bore can't be ruled out. I am just unhappy as they should have checked and out me in the picture completely before suggesting that a new head would fix the problems.

Most of my driving has been sustained high speed 90-100 kph (2200-2400 rpm) on highways with some low speed driving while game viewing on safaris.

The main question if if there is oil blowby would it be acceptable to just keep adding oil. After all the cost of oil is far lower then an engine out job. Could this lead to carbon build up in the combustion chamber and consequent damage?
AnswerID: 638998

Follow Up By: RMD - Tuesday, Jan 04, 2022 at 20:00

Tuesday, Jan 04, 2022 at 20:00
Amol
I agree there should have been a check of bores, easy to do. Oil is relatively cheap compared to rebuild or replacement. Make sure you use an oil which creates a good deal of rings to minimize oil use. Many cheap well advertised oils are not much good.
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FollowupID: 917852

Follow Up By: Amol K - Tuesday, Jan 04, 2022 at 20:06

Tuesday, Jan 04, 2022 at 20:06
Thanks. Taking it to Toyota for a diagnostic tomorrow. Shall report

Appreciate your replies.
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FollowupID: 917853

Follow Up By: axle - Thursday, Jan 06, 2022 at 11:29

Thursday, Jan 06, 2022 at 11:29
G/day Amol, I would think it depends on how much blowby is happening, only someone with experience can tell you. Not sure you will get that from Toyota, If the blowby is excessive, then adding oil may only be a very short term fix. There's all sorts of horrible things that can start to happen with excessive fumes entering the motor., It has to be bad though. Been there ..lol,


Cheers Axle
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FollowupID: 917877

Follow Up By: Amol K - Thursday, Jan 06, 2022 at 13:12

Thursday, Jan 06, 2022 at 13:12
The follow up is basically this -

Scraper ring appears to have collapsed and it's letting oil thru. Didn't seem to be leaving through from stem seals.

The Toyota garage have offered a fair amount of goodwill to open up the engine and carry out repairs which will include new pistons, rings, possible rebore/hone and the usual big bearings/seals etc. It will very likely be cheaper to go to an independent despite this.

Balls in my court to decide whether a 25 year old motor warrants this expense or I may just get rid of the problem.
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FollowupID: 917880

Follow Up By: PeterInSa - Friday, Jan 07, 2022 at 10:29

Friday, Jan 07, 2022 at 10:29
Re (Balls in my court to decide whether a 25 year old motor warrants this expense or I may just get rid of the problem.)

In a similar situation with my Landcruiser (400Km) I would most likely do a repair/engine swap, with my
Mechanic, as I know the vehicle compared to another 2nd hand vehicle and replacement Cruisers are a premium in Oz at the moment.
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FollowupID: 917886

Follow Up By: Amol K - Friday, Jan 07, 2022 at 13:42

Friday, Jan 07, 2022 at 13:42
That is sort of the dilemma.

I spent a fair amount around 20k km ago to have the gearbox and transfer case redone, new clutch and pressure plate, knuckles, halfshafts, diffs, wheel bearings, brakes, bushes etc. In short the transmission is good for another 250k, have a new head, radiator, water pump, timing belt, 4 new and 2 good tyres, 2 new batteries etc.
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FollowupID: 917887

Reply By: Amol K - Thursday, Jan 06, 2022 at 13:12

Thursday, Jan 06, 2022 at 13:12
Thanks everyone for your inputs. Greatly appreciated.
AnswerID: 639019

Reply By: Member - DOZER - Saturday, Jan 08, 2022 at 21:30

Saturday, Jan 08, 2022 at 21:30
When you overheat a motor, the alloy pistons grow quicker than the bores, scored bores result. Just keep driving g it and use thicker oil.
b4 you bag me out, walk a mile in my shoes, then your a mile away and have my shoes :)

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