Leaking valve guide seals? (1 Viewer)

How would you proceed if burning ~1 qt/500 miles?

  • Just buy more oil

    Votes: 2 11.1%
  • Replace valve guide seals, try to leave head on

    Votes: 1 5.6%
  • Pull head, have machine shop rebuild

    Votes: 12 66.7%
  • Full engine rebuild or new short block

    Votes: 1 5.6%
  • LS swap

    Votes: 2 11.1%
  • Use Barr's or similar

    Votes: 0 0.0%

  • Total voters
    18
Joined
Feb 5, 2009
Messages
30
Location
Knoxville, TN
 
 
My '93 1fz-fe is burning about a quart every 500 miles. Oil leaks are minimal. Spark plugs only have a few thousand miles but wet oil on them. I also did a leak down test (first I've done). The results seem reasonable from what I've read, though a few cylinders leaked out the intake.

My thought so far is valve guide seals. I just had the original catalytic converters replaced (rattling and excessive heat) so I would rather stop the oil consumption sooner than later. Current plan is to pull the head in October or November and have a machine shop rebuild it.

Does this seem like a reasonable diagnosis and solution?

Also, anyone happen to have recommendations for a good machine shop near Knoxville, TN to do the head work?


Leak down test results, engine hot:
Cyl. Psi in. Psi cyl
1. 80. 70
2. 80. 70
3. 80. 72
4. 80. 65
5. 80. 69
6. 80. 69

I read 20% leak is considered normal. 25% excessive. Leaks were out crank case (seemed normal, all seemed the same, and some also leaked out intake (so leaking intake valves I assume). No bubbles in coolant and none seemed to leak out exhaust.

I did take a few cylinders up close to 100 psi and the ratio did not change.


IMG_20200912_190323.jpg
IMG_20200912_190335.jpg


Valve cover gasket and tube seals are new. PCV is new. Most of the common oil leaks have new gaskets (currently leaks a drop in the garage every few weeks). I've tried different weight oils. All vacuum hoses are new. PAIR removed, EGR currently disabled. All evidence suggests the head gasket is original.
 
Joined
Apr 10, 2017
Messages
92
Location
Huntsville, AL
How many miles on the engine? My PHH blew and before I knew it my head was off 😱. My engine was at 190ish. Wasn’t burning quite as much oil as you but not too far off. I did the head gasket and everything else I possibly could at the same time. Was worth my peace of mind and I burn basically nothing now. There are also folks with 300k and no issues who have done far less.
 

fjc-man

SILVER Star
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Mar 21, 2014
Messages
562
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Commerce City, Colorado
 
Is the service history known for this 93? Maybe earlier in it’s life oil changes weren’t a big priority. Maybe the oil control ( bottom) rings are stuck causing the majority of your oil consumption. This wouldn’t really show up on a leakage test.
 
Joined
Feb 5, 2009
Messages
30
Location
Knoxville, TN
 
 
Thank you for your replies and thoughts.

240K miles on the engine. There is evidence of some maintenance, but much if it was not done well and not sure it was consistent over the years and previous owners.

Is the service history known for this 93? Maybe earlier in it’s life oil changes weren’t a big priority. Maybe the oil control ( bottom) rings are stuck causing the majority of your oil consumption. This wouldn’t really show up on a leakage test.
Any tests I can do before pulling the head to get an idea of ring condition? I have run some techron and also did seafoam in the crankcase for ~100 miles before an oil change. Would more of this maybe help?

One of my hopes in pulling the head was to get a good look at the cylinders.

Pulling the head is within budget (time and money). A full rebuild would be tight on both.
 

fjc-man

SILVER Star
Joined
Mar 21, 2014
Messages
562
Location
Commerce City, Colorado
 
I’m not real familiar with that engine, but maybe while the head is off you could get access to the connecting rod of cylinder #5 or #6 through the removal of just the stamped steel oil pan and push a piston out of cylinder.
This is really the only way to inspect the rings with the block still in the engine compartment.
 

ppc

M Go Blue
Joined
Aug 18, 2003
Messages
3,172
Location
Nashville, TN
 
 
 
During the leak down test if air exits from intake or exhaust then that indicates the valves are not sealing against the valve seats. Does not indicate anything good or bad related the valve seals that keeps oil from entering the combustion chamber from the top of the head. Air escaping through the crankcase indicates a problem with the piston rings not sealing against the cylinder bores. For the 1fz-fe motor high oil consumption is normally caused by the valve seals. Most head gasket replacements show the cylinder bores still have the original crosshatching even with engines with high mileage (300K). Not saying that isn't the problem but I question if the leak down test was performed properly. Most mechanics start with a regular compression test first to determine overall engine health before the leak down test.
 
Last edited:
Joined
Feb 5, 2009
Messages
30
Location
Knoxville, TN
 
 
I can try a compression test, too. I skipped it for a few reasons: money, time, the starter is a little tired (engine starts fine) and I figured if I was only gonna do one, the leak down would give more information.

It is quite possible I did not perform the leak down test properly. I took each cylinder to the top of it's compression stroke (borrowed someone's idea if using a dowle with a sharpie mark) and set the regulator to 80 psi.

That said, from my new and limited experience we with leak down tests, the leak rates are not too bad. 4 seems a little high, but the leak out the intake also seemed the highest (sound and feel). My thought is the intake leaks are due to carbon build up on the valves, which seems likely if oil was dripping down from leaking valve guide seals. At the very least it suggests a valve grind would help.

I have had the rig for two years and done a fair amount of work in it. I leaned to drive on a '93 back around 1993, and acceleration and power up hills fits with my recollection.

I have been suspecting valve guide seals as the cause of the oil consumption for a while. All the oil seals I've replaced have been hard and brittle, with some cracked - and these were on the outside of the engine.

At the end if the day, the main thing I would like to avoid, if possible, is doing the head work then realizing after the fact I should have done more. But honestly, even that would not be so bad. I could save up for a new/rebuilt short block and I would think the head work should still be good as long as I don't drive it much. It would just push out completion some.

We have a second child due in January. If more than head work is needed, the work will get pushed out for 6 months or longer regardless.

Thank you again for sharing your thoughts and comments, I really appreciate the help.
 

flintknapper

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May 22, 2004
Messages
8,104
Location
Deep East Texas
 
 
 
I was losing a lot oil down my valve stem guides...due to valve stem seals. The old ones were hard as rocks when I pulled them off and replaced them. After addressing that and few other leaks....I have NO oil drips and oil consumption is next to nothing now. Doubt I will have to add any (or very little) between oil changes now.
 
Joined
Jun 26, 2004
Messages
1,865
Location
east coast Canada
 
 
 
Remember folks this is a valve bucket shim style head. As miles build clearances close or get smaller. This means clearances may not be within spec and be tight leading to valves not sealing as well as they should.
Do a valve clearance check, maybe the low cylinders are tight leading to valve leakage.
If so replace shims to gain required clearance, compression should return if it’s the intake that is leaking. If it’s the exhaust it may or may not, if not you may have burnt valves!
 
Joined
May 13, 2012
Messages
34
Location
Seattle, WA/ Jacksonville, OR
 
Are you seeing any white or blue smoke from the exhaust after idling for ~20 minutes and then light tip in on the throttle? That is the easiest way to see worn seals/ oil consumption. I've done dozens of valve seal jobs for excessive oil consumption/ smoke and, when the cam is out and the cylinder has the leakdown guage on it, I rarely see high leakdown as a result of a failed valve guide seal. Think about it, for air to be leaking out of a worn valve seal, the valve itself would also have to not be sealing into the valve seat. Putting a new valve seal on, wouldn't fix that.

But, if you are going to try and do it on the car, There are a few kits available that facilitate that. A guy I work with uses this one with pretty good results when doing seals on the car. Although cylinder 6 may be a bit of a pain


Amazon product
 

flintknapper

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Messages
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Are you seeing any white or blue smoke from the exhaust after idling for ~20 minutes and then light tip in on the throttle? That is the easiest way to see worn seals/ oil consumption. I've done dozens of valve seal jobs for excessive oil consumption/ smoke and, when the cam is out and the cylinder has the leakdown guage on it, I rarely see high leakdown as a result of a failed valve guide seal. Think about it, for air to be leaking out of a worn valve seal, the valve itself would also have to not be sealing into the valve seat. Putting a new valve seal on, wouldn't fix that.

But, if you are going to try and do it on the car, There are a few kits available that facilitate that. A guy I work with uses this one with pretty good results when doing seals on the car. Although cylinder 6 may be a bit of a pain


Amazon product

I can't imagine trying to replace valve guide seals with the head still on the engine. They are a bear to remove (if mine is any indication). Installing them is no problem, but getting the old ones off was no easy task.
 
Joined
May 13, 2012
Messages
34
Location
Seattle, WA/ Jacksonville, OR
 
I've done them on other engines, but from the looks of this 1fz, with the spring/ seal recessed into the head, it would take some ingenuity, but not impossible. To remove the seal, I use hose pliers like these, the seem to grip and work better than valve seal specific ones that are in the kit that I use at work.
1600271482510.png
 
Joined
May 12, 2015
Messages
958
Location
Bakersfield, Ca
 
Mine's burning about the same or more, 220k on the engine.
I suspect the same and I'm just running it and going to deal with it later when I eventually do the head gasket.

Runs perfect and wouldn't hesitate to drive it anywhere currently
 

flintknapper

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Deep East Texas
 
 
 
I've done them on other engines, but from the looks of this 1fz, with the spring/ seal recessed into the head, it would take some ingenuity, but not impossible. To remove the seal, I use hose pliers like these, the seem to grip and work better than valve seal specific ones that are in the kit that I use at work.
View attachment 2437347
Grabbing them isn't the issue, it just takes a LOT pressure (straight up) and a bunch of twisting to get them to come off. I had my head up on a bench, had the correct tool and it was still a bear to get them off. I'm 6'-5" and 250 lbs and plenty strong, but still thought I was going to burst a vein in my neck getting them to come off. My engine had 316K miles on it....if that makes any difference.

The new ones go ON nicely.

VSS Pliers1.jpg
VS Seals1.jpg
VS Seals2.jpg
 
Joined
Jun 26, 2004
Messages
1,865
Location
east coast Canada
 
 
 
Some guys say use a propane torch to heat them up before trying to remove.

I have never done that and will never do it that way, just saying what I have been told to do when they are being difficult.

I use the old brute grunt force to remove them.

personally I would pull the head, after working on my engine last winter I know it would be easier to pull the head than struggle with it on there and possibly cause damage to the guides or worse yet the bucket bores.
 

fjc-man

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Looks like if the head was secured to the bench you could put a piece of wood across the valve cover mounting surface and place a prybar between the jaws of the pliers and against the wood to pop it off the valve guide.
 

landcruiser3DP

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tejas
/thanks/ to fj8ing for this one. lots of good intel i can see here. before i chunk through it i would like to ask:
1. nothing diagnostic to be learned from a oil sample analysis on this one from what i can gather?
2. how does the OP rule in or rule out rear main seal and/or oil pan arch seal leak?
THANKS
 

landcruiser3DP

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Remember folks this is a valve bucket shim style head. As miles build clearances close or get smaller. This means clearances may not be within spec and be tight leading to valves not sealing as well as they should.
Do a valve clearance check, maybe the low cylinders are tight leading to valve leakage.
If so replace shims to gain required clearance, compression should return if it’s the intake that is leaking. If it’s the exhaust it may or may not, if not you may have burnt valves!
fjbj40. have you got any appetite or patience for breaking this down? i realize that is a task ask but in case anyone can help:

“Remember folks this is a valve bucket shim style head.”
> anyone got any illustrations or pics that would help me understand this?

“As miles build clearances close or get smaller. This means clearances may not be within spec and be tight leading to valves not sealing as well as they should.”
> is this due to “valve seat recession”? or valve seat wear?

“Do a valve clearance check, maybe the low cylinders are tight leading to valve leakage.”
> what’s implied by too tight again and why does it lead to oil loss exactly?

“If so replace shims to gain required clearance, compression should return if it’s the intake that is leaking.”
> so this is getting off lucky with valve stem seals and new shimming for the intake valves? or did i edit that incorrectly?

“it’s the exhaust it may or may not, if not you may have burnt valves!“
> not following this exactly but i am gathering this is not getting off easy and it is new valve seats and new seals and maybe some decking on the head? or rings as well i guess?

trying to boot step myself in a daily basis...
 

fjc-man

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Commerce City, Colorado
 
So the bulk of the op’s oil consumption is most likely due to hard, poorly sealing valve guide stem seals. On the intake stroke, the piston is moving downwards pulling air / fuel past the opening intake valve. Sucking it into the cylinder. This sucking action is what is pulling oil past the worn seals. Then burned along with the fuel/air mixture.
 
Joined
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As engines age/wear valves opening and closing millions of times Leads to wear. The valve seat wears and the valve wears and stretches.

Valves are kept closed by the springs.

As the valves and seats wear the springs still keep the valves closed, however the valve moves “up” into the cylinder head.

The valve in these engines are open and closed by a camshaft. The camshaft lobes push on a bucket that has a recess In the top. In that recess is a shim, a changeable part that allows you to set the desired clearances set out in the manual.

The bucket rides inside the cylinder head in a bore. This bore is where the springs and retainers are that keep the valve closed.

So as the valve wears “up” The clearance closes or gets smaller. As this happens over mileage it needs to be adjusted by measuring and changing the shims. This rarely happens! I mean people not changing them.

So the increased wear causes the clearance to close up and eventually the valve does not seal, leading to lost compression and or burnt valves. Burnt valves require a cylinder head removal and repair.

Your oil burning Problem, if not low compression because of worn rings, is valve seals. To rule out low compression being worn rings you need to check valve clearances to make sure they are in spec. If out of spec and tight they will not seal giving an impression of worn cylinder rings.

Whew, that was a lot of typing for me 😳
 

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