1998 Explorer XLT Resurrection

[archer973]

Help! A new problem.

Time for an update. I received my new timing chain kit and installed it then set about the task of setting the timing. That process went well. As I have mentioned before, I did not use the recommended special tool kit. I made my own camshaft holder and chain tensioner. Both worked well. I also made my own strap wrench that I used to hold the crankshaft harmonic damper at TDC. I did not come up with a tool to hold the camshaft gears as I tightened the retainers, but I marked the alignment before torquing the bolt and monitored its position. Neither of the gears appeared to move as I torqued the bolt. I also had my wife watching the timing mark on the damper to make sure it didn't move as I tightened the bolts. I will describe my homemade tools in a later post.

NEW PROBLEM. I started cleaning engine parts and re-installing them on the engine. As I was cleaning the lower intake manifold section, I found an area that had overheated--extreme overheating. I also remembered that I had had trouble removing the retaining bolt at that point. The damage is located on the manifold tube feeding cylinder #6 . It appears that the mounting bolt (on the front side of this port) got extremely hot and the radiated heat overheated the nearby plastic which is now raised and pitted.

I decided to pull the head--had to order more parts--and try to determine why this bolt got so hot. I'm not a trained mechanic that can look at the inside of a cylinder and determine what is wrong so I need input. The internal appearance of cylinder #6 is different than #4 and #5 . The best word I have to describe it is it looks dryer. The exhaust valve appears scorched. Anyone have ideas for me?

Can a bad spark plug cause a cylinder to fire hot?
Could the problem be a clog in the cooling system?
Could the exhaust valve not have been closing completely?

 

[2000StreetRod]

lean condition?

I suspect a common cause of a hot cylinder is a lean condition. If injector 6 was partially clogged then cylinder 6 could run hot under load. Are there any signs of detonation on the spark plug, valves or piston? If the spark plug gap was excessive due to wear that could result in late spark and possible detonation.

The low compression on the passenger side would result in low power output from that side and shift the load to the good cylinders on the driver side. But that doesn't explain why cylinder 6 would run hotter than cylinders 4 and 5.

A blocked coolant port is a possibility but seems unlikely. Have you checked for a broken valve spring? Unfortunately, another special tool is needed to compress the valves. I purchased one that can be configured for the 4.0L and 4.6L SOHC valves and the 4.6L DOHC valves.

 

[archer973]

Hi 2000StreetRod,

Thanks for the quick reply. Before I answer your questions, I need to clarify an error in my previous post. It is the intake valve, not the exhaust valve, that appears different. I don't think scorched is the right description. It is dull and dry looking when compared to the other valves.

Before the car was turned over to me, a previous handyman had pulled all the plugs and replaced them so I don't have an answer about the plugs. There is no appearance of pitting on the valves or piston, so I think detonation is out. All valve springs are intact and appear to function properly. I suspect that the intake valve was not seating completely. I turned the cam enough to hold it open and the valve seat looks like it has some slight burning and pitting on it.

I think that the injector is the problem. There is some rust on the valve stem. I believe this came from rodent urine that collected around the injector during the years this car sat unused. I believe that leaked pass the injector and dripped onto the valve stem. This would indicate that the injector seals are defective. If that was the case, it would contribute to a lean condition. Then again, those seals may have been ok and the rodent urine made them deteriorate and leak. Fortunately the kit I ordered last night includes new o-rings for the injectors. It also has new valve stem seals.

I was already looking for a valve spring compression tool and I see the ones for Ford are a bit spendy. I haven't looked on Craigslist yet for a used one. I might luck out there.

Thanks again for your response. I appreciate your insight. Going back out to the garage now to strip this head and start cleaning it up. I will do both heads. Bought a complete kit for this.

TTFN!

 

[2000StreetRod]

valve spring compressor

See posts 16, 27 & 28 of the following thread:
DOHC 4.6L V8 build for information on the tool I purchased.

 

[archer973]

DIY Valve Spring Compressor

I had a choice of stopping work on this project while I wait for delivery of a valve spring compressor or I could save the purchase price, spend some time making my own tool and continue with the project. I had a few failed attempts at a homemade tool but I finally got it right and have removed the valves from the drivers side head. As I suspected, the intake valve for cylinder 6 has a very rough edge. I'm sure it was not seating completely and heat was escaping through it to overheat that small area of the head.

This is the fourth or fifth tool I've made for this job and I will post descriptions for them later. I don't think I can post pics since I'm not an elite member. I will try to figure out a way to make them available. Heck, I might pay the big bucks so I can post them here. We'll see.

 

[cycle61]

Following along, you're way deeper into that engine than I think I would be at this point. I'm down in the Mt Rainier area, beautiful winter we're having other than the complete lack of snow/rain.

 

[archer973]

Hi cycle61

Following along, you're way deeper into that engine than I think I would be at this point. I'm down in the Mt Rainier area, beautiful winter we're having other than the complete lack of snow/rain.

Hello and thanks for posting. I'm way deeper into this engine than I expected to be. But when I saw the indications of overheating I felt I couldn't put it back in the car without addressing the problem.

Mt. Rainier is a great area to live, especially if you like the outdoors. I currently live on San Juan Island but just made an offer on some property near Sedro Woolley. The wife and I hope to build our retirement home there. I've always liked the North Cascades--especially canoe trips on Ross Lake and hunting & fishing around Bake Lake.

We have had great weather this winter. Last summer too. Got a lot of outdoor projects done during the summer, but took time for camping and fishing as well. You've probably heard the old one-liner that people in Seattle don't tan, they rust. That just hasn't been true lately.

 

[archer973]

I received my new rebuild kit yesterday. I may regret this later, but in the interest of saving money I opted not to send the heads to a shop for testing and a valve job. Instead, I cleaned the valve seats with lacquer thinner. The valves I cleaned with a brass wire wheel. I replaced the valve stem seals (very easy to do), re-installed the valves, rockers, and camshaft. I set it aside while I started removing the passenger side head. I removed the cam and rockers before removing the head from the block. Then started backing off each head bolt slightly. The third one refused to budge and then my torx bit (3/8" drive T-55) slipped out of it. Before trying again, I examined the bolt and bit to make sure I would still have a good bite before trying again. The torx bit had actually twisted slightly. It wasn't a top quality bit--Harbor Freight. My wife is in the little town we live near. There is an Ace Hardware store there so I called her to see if she can get a new bit for me.

 

[archer973]

Mrs. Archer got me a new torx bit and I finished removing the head. I sort of expected what I found--valve strikes on all three pistons. I've removed and examined the valves and there doesn't appear to be much damage, but how much is too much? One of the intake valve stems is slightly bent so I'm going to replace that one. I'm open for advice here. Could there also be damage to the pistons other than the little half-moon dents? Should I bite the bullet and send this to a shop for a valve job? Is Ford a four-letter word?

 

[2000StreetRod]

damaged pistons

If your dings are no worse than those shown below your pistons should be OK to use. I think its most common for the exhaust valves to strike the pistons when the chain slips.

Do you have intake and exhaust valve dings?
Unless you have some way to bench test the valves for proper operation and sealing I suggest you take the head to a shop for inspection and repair. It would be a shame to get the head torqued down with a valve that doesn't function properly.

 

[cycle61]

At this point, I'd be strongly disinclined to reuse a valve that hit a piston hard enough to leave a mark. Even an imperceptible bend will leave it out of square and sealing poorly on the valve seat. Is replacing them with new or from a junkyard engine an option?

 

[archer973]

Thank you 2000StreetRod and cycle61

If your dings are no worse than those shown below your pistons should be OK to use. I think its most common for the exhaust valves to strike the pistons when the chain slips.

Do you have intake and exhaust valve dings?
Unless you have some way to bench test the valves for proper operation and sealing I suggest you take the head to a shop for inspection and repair. It would be a shame to get the head torqued down with a valve that doesn't function properly.

Thank you 2000StreetRod. The dings in my pistons look about the same as those in the photo. All three intake valves struck, but only one exhaust valve. I've ordered six new valves. I agree it would stink if I don't have this tested before reassembly. Now you have me wondering if I can fabricate my own test fixture. That will give me something to tinker with while I wait for the new valves to arrive.

At this point, I'd be strongly disinclined to reuse a valve that hit a piston hard enough to leave a mark. Even an imperceptible bend will leave it out of square and sealing poorly on the valve seat. Is replacing them with new or from a junkyard engine an option?

Thank you cycle61. I came to the same conclusion earlier today and ordered six new valves. They should be here middle of next week. Glad to have your input. It helps me feel better about my decision.

 

[archer973]

DIY Valve Test

I had already reassembled one head using the old valves after cleaning them with a brass wire wheel and cleaning the valve seats and head surfaces with lacquer thinner. But with the concern about valves on the second head, I decided to find a way to test the first head before mounting it on the engine. I did a search on the internet for DIY valve testing. One U-Tube video showed a test where they set the head on a bench with the exhaust ports pointing up. They poured water into the ports to see if it would leak through the valves. Their example head was straight off the engine--no rework done--and all the valves leaked, some more than others. If the water doesn't leak through, blow compressed air around the valve. If it seeps through, there will be bubbles rising in the water.

I tried this on the intake valves of my rebuilt head. Water did not seep through, but I did get bubbles when blowing compressed air around the valve. I wasn't completely satisfied with this test as there was no pressure against the valve face. I wanted a test fixture, but the only thing I had to mount the head on was the block. This is my solution...

I cut a rectangular sheet of gasket material out of some stock I had on hand. Punched eight holes in it for the bolts. I then cut a matching piece of thin sheet metal. I placed the sheet metal on the block, then the gasket, then mounted the head using the old head bolts. I removed the valve core from my compression tester hose and screwed the hose into a spark plug hole. The connector on the other end of this hose matches the quick connects on my air compressor, so I connected it to an air hose and now had 125 psi to the cylinder. I could not detect air leaking around the head mounting surface so I know the pressure in the cylinder was up around 125. I could detect air hissing--slightly--out of the exhaust port and intake port. I had the same result on all three cylinders.

Do I have a problem? I think that there will be some leakage and a leak down test is necessary at this point. Of course I don't have a leak down test instrument. Might be time to invest in one.

 

[cycle61]

Do I have a problem? I think that there will be some leakage and a leak down test is necessary at this point. Of course I don't have a leak down test instrument. Might be time to invest in one.

Based on a couple articles I found, some degree of leakage is acceptable, looks like 10-20% is normal for a used engine. This includes piston rings as well, so your leakage (valves only) should be less.

http://www.gregsengine.com/cylinder-leakdown-testing.html

 

[archer973]

Based on a couple articles I found, some degree of leakage is acceptable, looks like 10-20% is normal for a used engine. This includes piston rings as well, so your leakage (valves only) should be less.

Hi cycle61 and thank you. Good article you found. I had already found some of the things that are in it, but this is a more comprehensive source. I'm already looking into the purchase of a test instrument. I think it will be a good investment.

 

[archer973]

Welcome to spring!

Ok, I have one set of valves on order to replace those in the passenger side head where the valve strikes occurred. I've ordered a leak down tester also. Things are sort of on hold until they arrive. That gave me time to get my old Craftsman tiller out of the barn and get it running. It started right up, but then the float valve stuck open and the machine died with fuel pouring out. Had to disassemble the carb, clean it and also cut a new intake gasket. Its running good now and we are ready to till the garden.

 

[1998Exp]

Oh, the spring ritual of carburetor cleaning! I managed to finally avoid it by putting a bit fuel stabilizer in the tank and running the engine for few minutes before storing my gardening tools for the winter. Sorry for the off-topic response, but an engine is an engine, isn't it?

Ok, I have one set of valves on order to replace those in the passenger side head where the valve strikes occurred. I've ordered a leak down tester also. Things are sort of on hold until they arrive. That gave me time to get my old Craftsman tiller out of the barn and get it running. It started right up, but then the float valve stuck open and the machine died with fuel pouring out. Had to disassemble the carb, clean it and also cut a new intake gasket. Its running good now and we are ready to till the garden.

 

[archer973]

Oh, the spring ritual of carburetor cleaning! I managed to finally avoid it by putting a bit fuel stabilizer in the tank and running the engine for few minutes before storing my gardening tools for the winter. Sorry for the off-topic response, but an engine is an engine, isn't it?

Hi 1998Exp. Thank you for the input and I will try it next winter. My tiller has an inline fuel valve that I close and let the engine run till it burns out all the gas. I think a dry carb all winter may have contributed to this problem. I like your solution of running the machine to get stabilized fuel into the carb.

No need to apologize about the off-topic response. You read this because we have something in common--98 Explorer. But we have other things in common that we can share and help each other. I've enjoyed everyone's responses since I usually receive encouragement and valuable info.

 

[deadernie]

If you're not going to send the head out to get the once over you should at least lap the valves into the head after cleaning them. But for all of the time invested it would be good to know the heads were good to go before putting everything back together .

 

[archer973]

If you're not going to send the head out to get the once over you should at least lap the valves into the head after cleaning them. But for all of the time invested it would be good to know the heads were good to go before putting everything back together .

Hi, deadernie, and thank you for your post. Honestly, I had no idea what "lap the valves" meant, so I googled it. Great suggestion! After that little bit of research, I remembered that this is something my bro-in-law talked about doing when he was working on one of his cars several years ago. I will get his advice too since he has some hands-on experience. I truly appreciate your help and have decided you are right, this needs to be done since I'm not sending it to a machine shop.