Replace heads or engine?
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Laughing Gas
Joined: May 2003
Posts: 1,148
Likes: 1
From: Richmond, VA
Replace heads or engine?
The truck: 1992 Explorer. 4.0L V6.
Are heads replaced in sets? If the one is machined I know the intake manifold has to also be done but does this mean the other head has to be machined as well? I would think so.
Any thoughts here? With 210,000 miles is a new engine in order?
The problem is I have already replaced the gaskets and the #1 and #2 cylinders now have the same steady low (90 psig) pressure as compared with the other side which has 130 psig.
I intend to pull the left head and check for warpage and fluxed if needed.
I know if the cylinder walls or jacket is cracked the decision is made.
Thanks
Reg
Are heads replaced in sets? If the one is machined I know the intake manifold has to also be done but does this mean the other head has to be machined as well? I would think so.
Any thoughts here? With 210,000 miles is a new engine in order?
The problem is I have already replaced the gaskets and the #1 and #2 cylinders now have the same steady low (90 psig) pressure as compared with the other side which has 130 psig.
I intend to pull the left head and check for warpage and fluxed if needed.
I know if the cylinder walls or jacket is cracked the decision is made.
Thanks
Reg
Last edited by afinepoint; Nov 25, 2003 at 10:05 PM.
Thread Starter
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Laughing Gas
Joined: May 2003
Posts: 1,148
Likes: 1
From: Richmond, VA
Thanks. I took the truck in this morning. The head mechanic feels the late ignition reading on the vacuum gage doesn't mean much. He also implied that 90 psig is not that low. Is it?
The Haynes manual was pretty insistent that equal "low" reading on adjacent cylinders is a gasket leak between the two.
The truck ran better this morning. Rough but no CHECK ENGINE light after warmed up. I have not changed the oil since replacing the gaskets as I am trying to flush the system. Could water in the oil cause this problem? Water did enter the cylinders.
Can heads be machined with the exhaust manifolds in place?
Again I appreciate the advice.
Reg
The Haynes manual was pretty insistent that equal "low" reading on adjacent cylinders is a gasket leak between the two.
The truck ran better this morning. Rough but no CHECK ENGINE light after warmed up. I have not changed the oil since replacing the gaskets as I am trying to flush the system. Could water in the oil cause this problem? Water did enter the cylinders.
Can heads be machined with the exhaust manifolds in place?
Again I appreciate the advice.
Reg
Posting Guru
Joined: Jan 2003
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From: Still under the hood in O
Change that oil imediately!!
Water in the oil will run through the bearings and may cause them to fail. At least, it could cause rust pitting - not good. Also it could affect oil pressure.
90PSI is low - anything below 100 should be investigated.
Oil in the water will not affect cylinder compression.
The exhaust manifolds must be removed from the heads for machine work.
Usually, you don't need to machine the intake unless alot of material is removed from the head. If it does call for milling the intake, yes I would also do the other head. If this is done you will need to check for proper valvetrain geometry since this may change that as well (shorter pushrods may be needed).
Water in the oil will run through the bearings and may cause them to fail. At least, it could cause rust pitting - not good. Also it could affect oil pressure.
90PSI is low - anything below 100 should be investigated.
Oil in the water will not affect cylinder compression.
The exhaust manifolds must be removed from the heads for machine work.
Usually, you don't need to machine the intake unless alot of material is removed from the head. If it does call for milling the intake, yes I would also do the other head. If this is done you will need to check for proper valvetrain geometry since this may change that as well (shorter pushrods may be needed).
Logistics Pro
Joined: Jan 2002
Posts: 4,907
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From: suburban atlanta
DO the leakdown test, as JW said. If you don't, you might just as well replace the whole thing. If the rest of the engine is in good shape, the head renewal will give it a good increase in life. Be aware of the valve geometry, as it has caught many mech. "duh, it won't run smooth..." Hydraulic lifters can take care of a bunch of clearance change, but they have their limits ...
tom
tom
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Laughing Gas
Joined: May 2003
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From: Richmond, VA
Took the heads off last night. From start to heads on the workbench in two hours! That may be the height of the success story because . ..
The #4 cylinder was 1/3 full of water. #1 shows signs of wettness. The top of the block shows significantly more water going places it should not. I think alot is just due to watery oil being pumped throughout the engine.
Here's a question for you guys. Why is the gasket designed to cover some of the water channels? I looked at the old gaskets and the ones I just put on. In some places the new has small holes above coolant channels that the old does not have and in other places it completely covers the same channels. Shouldn't all of the channels be open? Or am I missing something here?
Reg
The #4 cylinder was 1/3 full of water. #1 shows signs of wettness. The top of the block shows significantly more water going places it should not. I think alot is just due to watery oil being pumped throughout the engine.
Here's a question for you guys. Why is the gasket designed to cover some of the water channels? I looked at the old gaskets and the ones I just put on. In some places the new has small holes above coolant channels that the old does not have and in other places it completely covers the same channels. Shouldn't all of the channels be open? Or am I missing something here?
Reg
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I must have missed something. afinepoint, what did the mechanic say? If that thing was 1/3 full of water something is really messed up, did you drain the coolant before you pulled the heads? Sorry if I am asking you weird questions, I am trying to get a mental picture if you will of what is going on. As far as the gaskets go, again I know little about the 4.0, could there be slight differeces in the years and maybe you were given the wrong on? Are you replacing the heads altogether? later
Last edited by jwtaylor; Nov 29, 2003 at 03:10 PM.
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Logistics Pro
Joined: Jan 2002
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From: suburban atlanta
*Generally* the gasquets will be the same on both heads, BUT, one will be put on 'upside down'. Take note of the word FRONT embossed on most FoMoCo gaskets, and make sure it is towards the front of the engine.
The coolant flow will be 'improved' by having smaller holes at the front, and larger at the rear because the pump is at the front, and the coolant would tend to go the shortest route.. and leave the rear of the engine a tad warm.
The old and new should NOT have a lot of difference. If you have a real concern, take them both to the parts house for a comparison. Make sure that you don't have a OHC set or vice-versa.
tom
The coolant flow will be 'improved' by having smaller holes at the front, and larger at the rear because the pump is at the front, and the coolant would tend to go the shortest route.. and leave the rear of the engine a tad warm.
The old and new should NOT have a lot of difference. If you have a real concern, take them both to the parts house for a comparison. Make sure that you don't have a OHC set or vice-versa.
tom
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Thread Starter
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Laughing Gas
Joined: May 2003
Posts: 1,148
Likes: 1
From: Richmond, VA
The machine shop looked at the heads Monday morning. #1 and #2 show a crack between them. That head is shot. Also explains the equal "low" 90 psig betweem them. The other head shows a propagating crack. New heads are on order. $500 for the pair.
I installed the gaskets correctly. According to the machinist over time the design of the gaskets have changed to address cooling problems with these heads. The closed off ports are to hold water around that part of the engine. The coolant still circulates just slower.
That magnetic fluxing is amazing. The crack became as plain as ink on paper. He suggested a bottom end job as well but $1100 to pull and replace the engine (by another shop) + $1700 to do the heads? Don't think do. I'll do it later when I get a stand and lift.
The heads arrive in two weeks. I keep you posted.
Thanks,
Reg
I installed the gaskets correctly. According to the machinist over time the design of the gaskets have changed to address cooling problems with these heads. The closed off ports are to hold water around that part of the engine. The coolant still circulates just slower.
That magnetic fluxing is amazing. The crack became as plain as ink on paper. He suggested a bottom end job as well but $1100 to pull and replace the engine (by another shop) + $1700 to do the heads? Don't think do. I'll do it later when I get a stand and lift.
The heads arrive in two weeks. I keep you posted.
Thanks,
Reg
Last edited by afinepoint; Dec 2, 2003 at 12:28 AM.
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Laughing Gas
Joined: May 2003
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From: Richmond, VA
The new heads came in and are on. I finished putting all back together today. A couple of odd things.
1. There is a hissing/spitting sound coming from the left driver's) side. It is not loud. It's coming from the valve cover/exhaust manifold area. The noise it is in rhythmic with the idle. I can smell no exhaust leak. It really sounds like it's coming from under the valve cover. The mechanic says it sounds like a compression leak. I know the plugs are tight.
2. Gunpower smell. After all of the oil and dirt burned off the manifolds a gunpower smell lingers. The exhaust did fill with water when the head gasket blew. My mechanic thinks the catalytic converter has gone because of the flooding. The exhaust is clear.
Any ideas.
Reg
1. There is a hissing/spitting sound coming from the left driver's) side. It is not loud. It's coming from the valve cover/exhaust manifold area. The noise it is in rhythmic with the idle. I can smell no exhaust leak. It really sounds like it's coming from under the valve cover. The mechanic says it sounds like a compression leak. I know the plugs are tight.
2. Gunpower smell. After all of the oil and dirt burned off the manifolds a gunpower smell lingers. The exhaust did fill with water when the head gasket blew. My mechanic thinks the catalytic converter has gone because of the flooding. The exhaust is clear.
Any ideas.
Reg
Logistics Pro
Joined: Jan 2002
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From: suburban atlanta
Ummh... If the sound changes with RPM, then it is not something such as coolant leaking onto the exhaust manifold and spittiing & popping.. Does it sound as if there is a real hot spot on the head, such as a boiling sound .. like an old water heater makes when it has sediment? I'd be checking the exhaust manifolds for flatness and good contact with the cylinder head.
As far as the odor goes, if the heads were painted, you will get a 'new engine' smell for a while. A bum converter will stop converting, and just pass exhaust like an old muffler. It will not affect the odor, as it is 'spent' and does not 'catalyze' the reaction any more, so the reaction does not take place, or at least not as much.
Wish I could describe exhaust leak. THey can sound like a spark plug that has been blown out of the head, or chirp, and other sounds. Anyway, good luck.
tom
As far as the odor goes, if the heads were painted, you will get a 'new engine' smell for a while. A bum converter will stop converting, and just pass exhaust like an old muffler. It will not affect the odor, as it is 'spent' and does not 'catalyze' the reaction any more, so the reaction does not take place, or at least not as much.
Wish I could describe exhaust leak. THey can sound like a spark plug that has been blown out of the head, or chirp, and other sounds. Anyway, good luck.
tom
Thread Starter
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Laughing Gas
Joined: May 2003
Posts: 1,148
Likes: 1
From: Richmond, VA
Tomw,
The sound is in time with the idle. Like someone letting air out of a tire in ryhthm with the engine.
The engine runs roughly sounding like a (quiet) diesel. Acceleration is weak. Heres the reallly odd thing. The engine loses power and gets rougher when backing up particularly backing uphill. The tank is full with fresh gas.
At idle the engine is almost normal though not smooth.
I put a code reader on the engine but the codes that came up are not in the manual or the analyzer book. I read them twice. That was with the engine on. The engine off test passes.
I know I got water into the oil when the first gasket blew. I have drained the old oil added new and plan to change out the oil after a few more miles. The engine sat open to the garage atmosphere for a month and did get rust on one of the cylinder walls. On the hissing side. The rust cleaned right off.
I keep thinking it's something I forgot to hookup or has failed.
One code that was in the book was #29 "unable to read speed sensor".
I am going to run more tests tomorrow.
Reg
The sound is in time with the idle. Like someone letting air out of a tire in ryhthm with the engine.
The engine runs roughly sounding like a (quiet) diesel. Acceleration is weak. Heres the reallly odd thing. The engine loses power and gets rougher when backing up particularly backing uphill. The tank is full with fresh gas.
At idle the engine is almost normal though not smooth.
I put a code reader on the engine but the codes that came up are not in the manual or the analyzer book. I read them twice. That was with the engine on. The engine off test passes.
I know I got water into the oil when the first gasket blew. I have drained the old oil added new and plan to change out the oil after a few more miles. The engine sat open to the garage atmosphere for a month and did get rust on one of the cylinder walls. On the hissing side. The rust cleaned right off.
I keep thinking it's something I forgot to hookup or has failed.
One code that was in the book was #29 "unable to read speed sensor".
I am going to run more tests tomorrow.
Reg
Last edited by afinepoint; Jan 13, 2004 at 07:13 PM.
Logistics Pro
Joined: Jan 2002
Posts: 4,907
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From: suburban atlanta
Didja follow the book procedure when adjusting the valves? The 'daddy' to the 4.0 had rocker shafts & mechanical lifters, and I don't own one at all, but when they got to the 2.9 they went to hydraulic lifters. They need an initial adjustment, I think, to set the lifter piston in the middle of its travel.
The 'tire' noise (kind of a whistley sound?) makes me think of an exhaust gasket leaking.
tom
The 'tire' noise (kind of a whistley sound?) makes me think of an exhaust gasket leaking.
tom
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Laughing Gas
Joined: May 2003
Posts: 1,148
Likes: 1
From: Richmond, VA
Tomw,
Idle fixed. Spark plug wire problem. Fixing the idle has also quieted the hissing but it's still there.
This engine does not use exhaust manifold gaskets. There were none when I disassembled the engine and the manual states that as long as the surfaces are true none are needed. I thought about installing some but did not because of alignment concerns and adding more parts. Simplify right?
I have the gaskets. This side is easier to get to so I may add one before the manifold bolts really grab hold.
Reg
Idle fixed. Spark plug wire problem. Fixing the idle has also quieted the hissing but it's still there.
This engine does not use exhaust manifold gaskets. There were none when I disassembled the engine and the manual states that as long as the surfaces are true none are needed. I thought about installing some but did not because of alignment concerns and adding more parts. Simplify right?
I have the gaskets. This side is easier to get to so I may add one before the manifold bolts really grab hold.
Reg
Last edited by afinepoint; Jan 14, 2004 at 09:12 AM.
