1994 High Oil Consumption (1 Viewer)

Joined
Oct 13, 2019
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Sacramento
I have a new to me FZJ80 that is burning about 1Qt per 150 miles. I've read related threads and haven't seen anyone with anything near this rate. There are only a few drops of oil leaking every couple of weeks when it's left parked and I cannot see any leaking while it's running. No blue smoke at start up or when driving at high RPM. PCV just replaced and the prior owner is a family member who hadn't noticed any excessive consumption and had it smoged right before I got it at the end of 2019...seems to be a new issue. I wanted to know if anyone has any guesses about likely causes, before/if I take it to the shop. Any feedback would be appreciated!
 

baldilocks

Battle Ground, WA
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What year and how many miles on the engine? What type and weight motor are you running? Have you inspected the spark plugs and throttle body bore for oiliness? Gas mileage drop or Power/performance deterioration since you bought it?

I’d do a compression leak down test to verify rings and valves are not leaking.

The oil is either leaking onto the ground or it’s being pushed out the exhaust pipe.
 
Joined
Jan 26, 2010
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Clovis, CA
A leaking 80 won’t leave drips on the ground. If it does, it’s leaking bad. It’s best to pull the stone guard that’s behind the steering stabilizer and look for oil build up. That’s a lot of oil loss/consumption.

How long does it take for you to cover 150 miles, a week, a month?
 

voodu3

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Signal Mountain,TN
How many times has this happened? Has the valve cover been off? The reason I ask is when I first got my 80 I took it to my local dealer to get a triage list (before I learned they have no interest or ability to work on old trucks). They did the valve cover gasket and few other things while I had it there and they didn’t get the valve cover sealed. I lost almost two quarts of oil in about 100 miles. It was basically running out the back of the valve cover. It was only leaking when the truck was running.
 
Joined
Jun 8, 2007
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Houston
Of no visible leaks, worn valve guides or bad rings. At 180k mine used a bit of oil but, when it popped the headgasket I had the head rebuilt and oil consumption went to 0. The exhaust valve guides were worn pretty bad. 304k miles on it now and the oil level barely moves at 5k mile intervals.
 
Joined
Jul 21, 2015
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Bend, OR
A high mile 80 is a deceptive oil leaker... it doesn't really drip rather it coats the whole underside and fills up the little nooks and crannies.

I'd degrease/clean the engine and underside really well and see if you can find any leaks first. A quart burned per 150 miles is like a two stroke engine, you would see/smell/feel/notice something...

In the meantime do a search on common oil leaks and you'll find a ton of threads.
 

ppc

M Go Blue
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Are you consistently reading the dipstick or are you adding oil based upon the low level dash light. The dash light has a history of false readings .
 
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Jan 15, 2017
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P Town!
A year ago my head gasket s*** the bed. I had the head rebuilt and reinstalled it. I immediately started going through a quart of oil every 75-80 miles. Before that, it was a quart every five hundred miles or so. I then had the engine rebuilt and no longer burn oil.
 
Joined
Oct 13, 2019
Messages
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Location
Sacramento
Thank you all for the feedback, I've been going back and forth with mechanics and should have been checking this thread more. The valve cover gasket and spark plug & tube seals were replaced right before I got the vehicle, according to my father/prior owner there was no prior noticeable oil loss when he had it and it passed CA smog before it went to the shop for the gasket work. I've been checking the dipstick and not solely relying on the indicator light.

Using 10w-30 it was going through about 1Q every 100 miles, now using 20w50 and it's down to about 1Q every 200 miles. If the truck is left standing at idle for 30min there is no dripping oil.

There is usually oil build up on the bottom of the power steering pump (Lowest front corner of the driver side), I don't see much oil on the rock guard plate. It is also usually wet with oil near the forward facing vent on the transmission (?) and on the black plate that protects what I believe is the transmission pan gaurd/cover.

It was recommended that I look at the oil pump cover, but I don't see much oil spray in side that area, thought I have not removed the plate.

A mechanic said he did a throttle snap test to see if it was an issue with the valves and also looked for oil burning at start up and said he didn't see any. I've not seen any oil smoke come out of the tail pipe and the compression on all cylinders is at factory spec.

I'm a total newbie as trying to be a mechanic and greatly appreciate all of your advice!
 
Joined
Nov 9, 2012
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Olathe, KS, USA
Thank you all for the feedback, I've been going back and forth with mechanics and should have been checking this thread more. The valve cover gasket and spark plug & tube seals were replaced right before I got the vehicle, according to my father/prior owner there was no prior noticeable oil loss when he had it and it passed CA smog before it went to the shop for the gasket work. I've been checking the dipstick and not solely relying on the indicator light.

Using 10w-30 it was going through about 1Q every 100 miles, now using 20w50 and it's down to about 1Q every 200 miles. If the truck is left standing at idle for 30min there is no dripping oil.

There is usually oil build up on the bottom of the power steering pump (Lowest front corner of the driver side), I don't see much oil on the rock guard plate. It is also usually wet with oil near the forward facing vent on the transmission (?) and on the black plate that protects what I believe is the transmission pan gaurd/cover.

It was recommended that I look at the oil pump cover, but I don't see much oil spray in side that area, thought I have not removed the plate.

A mechanic said he did a throttle snap test to see if it was an issue with the valves and also looked for oil burning at start up and said he didn't see any. I've not seen any oil smoke come out of the tail pipe and the compression on all cylinders is at factory spec.

I'm a total newbie as trying to be a mechanic and greatly appreciate all of your advice!

Blue Smoke is oil.
Black smoke is fuel.
White smoke is coolant.

Blue smoke on start-up is valve seals/guides.
Blue smoke on acceleration is rings
Blue smoke on deceleration is valve seals/guides

Check the PCV valve and hose. It may be sucking huge amounts of oil through there. If the catalytic converters are doing their job, you'll not see a LOT of smoke, but 1qt/200 miles is a LOT. You should see that, whether it's dripping or burning.

You may also request a compression test (note that it's done warm. Also wet and dry!)
Also request a leak-down test. This will tells us top end, bottom end, rings, valve seals, valves.

Park over a large piece of clean cardboard overnight after a long warm-up drive. Then you'll see what you're actually dripping and what color it is, and WHERE it's dripping down from. Post a picture or seven on here with the cardboard and truck so we can help you pinpoint.

We have all encountered mechanics that are not the best, so collectively, we have worked through some really interesting stuff.

Stay focused.
 
Joined
Oct 13, 2019
Messages
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Location
Sacramento
How many times has this happened? Has the valve cover been off? The reason I ask is when I first got my 80 I took it to my local dealer to get a triage list (before I learned they have no interest or ability to work on old trucks). They did the valve cover gasket and few other things while I had it there and they didn’t get the valve cover sealed. I lost almost two quarts of oil in about 100 miles. It was basically running out the back of the valve cover. It was only leaking when the truck was running.

Found that oil is leaking out of the back side of the valve cover gasket. Right before I got the vehicle the gasket was serviced at a shop, after hearing from you I decided to clean up the area around the gasket, drove it for a while and then found that fresh oil was leaking out. This may have been the oil that was collecting around the rear mail seal. I'm going to resolve this and then update, thanks!
 
Joined
Nov 9, 2012
Messages
10,564
Location
Olathe, KS, USA
Found that oil is leaking out of the back side of the valve cover gasket. Right before I got the vehicle the gasket was serviced at a shop, after hearing from you I decided to clean up the area around the gasket, drove it for a while and then found that fresh oil was leaking out. This may have been the oil that was collecting around the rear mail seal. I'm going to resolve this and then update, thanks!
Be aware that it's VERY likely that one or both of the rear bolts on the VC are missing, stripped, or broke off. Use only OEM parts.
 
Joined
Oct 13, 2019
Messages
8
Location
Sacramento
Update: Valve Cover gasket is replaced, driven it almost 150 miles and haven't seen the level on the dip stick change, I'm feeling optimistic with fingers crossed! Will update when there's more miles.

Had put 20w50 in to manage the high oil loss, but am thinking that I should put a thinner oil in?...

Can anyone explain why folks run a thicker than factory recommended 10w30?

Also had a seasonal oil viscosity question: summer temps in the Sierra range get down to low 40's and high 30's; the winters are mid 20's into the low teens. I believe the service manual says 10w30 is recommended down to 0, but I wanted to know how the thicker oils' limits compare. Does anyone have any educated guesses about thresholds for 15w40....or anything else you recommend using based on temp ranges?

I assume that conventional is preferred to synthetic

Thank you all for all the information on the oil loss and have a Happy 4th of July!!
 
Joined
Jul 21, 2015
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Bend, OR
Does anyone have any educated guesses about thresholds for 15w40....or anything else you recommend using based on temp ranges?

I assume that conventional is preferred to synthetic

Thank you all for all the information on the oil loss and have a Happy 4th of July!!

As a data point I use 10w40 Mobil 1 High Mileage synthetic. The lowest temp we see here is around -30F, the highest about 105F. I'm sure 10w30 would be fine as well but with 325k miles I went with the slightly thicker oil.

As for conventional vs synthetic do a search and you'll find all kinds of viewpoints. In my view conventional is really only preferred on when you have a lot of leaks or use a lot of oil since its cheaper and may leak slightly less on an old engine.
 
Joined
Nov 24, 2018
Messages
181
Location
Northern NM
You shroud go back to a lower weight oil, 10w30 is fine year around.
I have been running 5 qts of 10w30 and one qt of marvel mystery oil. Works great cruiser loves it.
 

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