Landcruiser 80s 1Fz-Fe Burnt Valve ?

Submitted: Thursday, Feb 04, 2010 at 14:18
ThreadID: 75767 Views:7612 Replies:5 FollowUps:3
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Hi

Got an 80s on gas for the past few years and I've noticed a progressive lack of power and a funny noise from the exhaust/head that sounds like a leak (but isn't because i cant find the exhaust leak anywhere).
Anyway after doing some reading it sounds like it could be a burnt valve. Does anyone know how to diagnose one before I spend $3k on a new head?


Cheers,

Fil
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Reply By: dbish - Thursday, Feb 04, 2010 at 14:50

Thursday, Feb 04, 2010 at 14:50
First thing to do is a Cylinder compression test, cylinders with burnt valves will be lower, Daryl
AnswerID: 402646

Reply By: oldfart1953 - Thursday, Feb 04, 2010 at 15:44

Thursday, Feb 04, 2010 at 15:44
Compression test yes.....
Engine up to normal operating temp (N.O.T.) Remove plugs, keep in order inspection of the plugs can tell a lot to the trained eye.
Do a dry test first with wide open throttle (W.O.T.)crank engine over the same number of times for each cylinder say 6 or 7 times. Record readings. Then do a wet test this involves putting three squirts of clean engine oil into each cylinder just before you connect the compression guage to that cylinder.
Record & compare results from wet & dry tests.
If there is a marked increase in compression with the wet test this would more than likely indicate worn rings on that cylinder.
Low compression with both wet & dry test would more than limkely indicate a burnt vale & this will be odds on to be an exhaust valve as they run a lot hotter than the inlet valve.
Low compression on adjoining cylinders usually indicate a blowen head gasket.
Ideally you want the results to be no more than10% variation from the highest to the lowest reading.
Hope this helps

CU down the road
Tony H
Insanity doesnt run in my family.... it gallops!

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AnswerID: 402655

Follow Up By: Bubbles - Thursday, Feb 04, 2010 at 16:40

Thursday, Feb 04, 2010 at 16:40
Thanks Tony

Thats an awesome walk-through! Hopefully get it done early next week once the compression tester turns up.
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Follow Up By: oldfart1953 - Friday, Feb 05, 2010 at 09:54

Friday, Feb 05, 2010 at 09:54
Sorry I forgot to say that you really should disable/disconnect the fuel supply while doing a compression test....remove fuse or relay....otherwise you will be fueling the engine while your cranking it over...with the possibility of a 'big bang'

Tony H
Insanity doesnt run in my family.... it gallops!

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Reply By: nowimnumberone - Thursday, Feb 04, 2010 at 21:29

Thursday, Feb 04, 2010 at 21:29
$3000 for a landcruiser head job sounds way to dear if it is a head make sure get get a few quotes
cheers
AnswerID: 402713

Follow Up By: Alloy c/t - Friday, Feb 05, 2010 at 12:27

Friday, Feb 05, 2010 at 12:27
Charlie from 2 and a half men has been known to pay twice that amount, LOL.
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Reply By: Bubbles - Monday, Mar 01, 2010 at 13:24

Monday, Mar 01, 2010 at 13:24
So I did a compression test yesterday and it came up with some obvious results:

1: 180psi
2: 180psi
3: 180psi
4: 30psi
5: 180psi
6: 180psi

So definitely a burn out valve or seat. Does anyone have any recommendations on if I should go with head replacement or do a recond'd long or short motor? Any places I should talk to first in Adelaide area?


Cheers

Fil
AnswerID: 406666

Reply By: Bubbles - Monday, Mar 22, 2010 at 14:50

Monday, Mar 22, 2010 at 14:50
OK

Just if anyone else goes through this I thought I would give a costing.

Dropped car off to a S.A. Cylinder Heads. He took the head off, replaced all exhaust seats with lpg seats and all valves with lpg valves. Cleaned the head up, re-shimmed the tappets and put it all back together with new seals.
He also took the sump off, cleaned it all out, changed oil filter, oil and coolant, replaced 3 coolant hoses and the HT leads.
Gave the car a once over and let me know what else needs to be done.
All work was completed in one week and cost me $2595.

Very happy and will be returning there for other work.

Cheers!

Fil
AnswerID: 409909

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