420A Help with damaged spark plug

[Cypherfox]

I would like advice or direction to get my car fixed properly.
These are parts that I replaced and not updated on my profile -spark plugs (ngk IX Iridium 6418) and Duralast gold wire set. The care ran with no noticeable changes. Two days later I was driving on the highway (idling at 55mph) when the car just shut off. I did not hear any noises nor was there any smoke coming from the engine. I pulled over and tried cranking the engine and it would not start. I had it towed home and started looking for the problem. The car cranks flowly but will not start. I pulled the sparked plugs and saw that cylinder four had major damage to the electrode. What should I do to diagnose this problem? I'm thinking I should pull the valve cover and engine head assembly, check timing belt and components, have a machine shop check the head for damage, reassemble if everything is okay.

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[JeffGS-T97]

Pull the timing cover see if the crank position sensor is still in one piece. If the crank has play the trigger plate will destroy that sensor and the car will immediately shut off. If it did break hopefully if thats what happened the timing belt didn't jump time. If you have a code device the sensor should show up on there if you were trying to start it after blowing the Crank sensor.

Oh im sorry i answered too quickly i just realized your engine is the 420a and this issue may not be common for your engine.

 

[Cypherfox]

I’m going to remove the valve cover and timing cover. I’ll post a update. I feel like there is serious mechanic damage inside the cylinder since the spark plug electrode is pushed so far in. I know I torqued it correctly.

 

[JeffGS-T97]

I’m going to remove the valve cover and timing cover. I’ll post a update. I feel like there is serious mechanic damage inside the cylinder since the spark plug electrode is pushed so far in. I know I torqued it correctly.

I agree unfortunately, i hope its not too bad. The damage to that plug is nasty i have literally never seen that before. Sounds like you got a good game plan set, good luck on your repairs.

 

[dustyboner]

you should plan on pulling the head. if its an issue with the timing belt your gonna have bent valves. Even if its not, there has to be a chunk of something bouncing around in the cylinder to damage the plug like that.

 

[BLACK'98DSM]

420a crankshaft position sensor is on the back of the block below the intake manifold.

I've ran mine on 3 cylinders once and it started right up and drove (long story) so I'm thinking there is further damage.

 

[Cypherfox]

I’m planning on pulling the head off and getting it checked by a machine shop. It’s my first time doing this so I’m doing it carefully. I’m not sure about a few things though. Is it necessary to get the timing on TDC if I’m going to remove the engine head? Is it okay if I have the engine sitting without any oil? I’ll take some pictures of what I have done so far and post later today.

 

[Dericsh]

You’re gonna need it on TDC to reinstall the belt, so you might as well put it there before you remove it. If you can, that is, it’s not broken?
It’s fine to leave it sitting without oil while you’re repairing it. When it’s not running, the oil is just sitting in the pan anyway.

 

[JeffGS-T97]

I’m planning on pulling the head off and getting it checked by a machine shop. It’s my first time doing this so I’m doing it carefully. I’m not sure about a few things though. Is it necessary to get the timing on TDC if I’m going to remove the engine head? Is it okay if I have the engine sitting without any oil? I’ll take some pictures of what I have done so far and post later today.

Lots of pictures and organizing bolts and parts during your disassembly is highly recommended. It already sounds like you got the right idea so far but it would be wise to reference the manual to make sure you follow the correct order of operation to prevent damaging anything or doing unessassary work.

 

[1990TSIAWDTALON]

I’m going to remove the valve cover and timing cover. I’ll post a update. I feel like there is serious mechanic damage inside the cylinder since the spark plug electrode is pushed so far in. I know I torqued it correctly.

Use a borescope in the sparkplug hole and see what it shows.

 

[JeffGS-T97]

I totally agree , i keep forgetting to add one to the tool collection. Good call

 

[1990TSIAWDTALON]

Handy for all kinds of things Jeff!

 

[Cypherfox]

Lots of pictures and organizing bolts and parts during your disassembly is highly recommended. It already sounds like you got the right idea so far but it would be wise to reference the manual to make sure you follow the correct order of operation to prevent damaging anything or doing unessassary work

I understand and agree that labeling and referencing bolts, fasteners, electrical conections, etc. is important. I'm using both "Haynes" manual and "AllData" as reference guides. Although I still get stuck or I'm unsure about some things. Exp. right now I'm having trouble removing the motor mount bracket that is near the timing cover. I cant get the two bolts far enough out so that i can remove them. I could raise or lower the engine so that i cant have more room to remove them. i could loosen parts adjacent to the mount; timing cover, power steering lines, egr lines, and maybe that will give me more wiggle room. Maybe im doing the whole thing wrong . I"ll attach pictures of what I see.

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[JeffGS-T97]

The numbers on the page are they the order of operation im guessing?
I never dug that far into my 420a back in the day, black98dsm is a very knowledgeable guy on the 420a he probably knows a trick or two on that little issue. In the meantime ill dig a bit and see if i can find something.

https://www.dsmtuners.com/threads/help-removing-motor-mount-bracket.203484/

Heres a thread of someone who had the same trouble.

 

[TerminalTalon]

You might need to remove/install with them in the bracket.

 

[BLACK'98DSM]

That bracket is a pain to remove with the engine in the car. But it's possible. Done it twice. What I did is put a jack and block of wood on the oil pan and jack the engine up high enough to slide those bolts out. Then it's a matter of wiggling that bracket out. It fits tightly in there.

 

[JeffGS-T97]

I'm not sure how much of the bolt threads, but maybe shorter ones If possible could make it easier in the future. Just spit balling not sure if would actually work.

 

[Cypherfox]

The numbers on the page are they the order of operation im guessing?
I never dug that far into my 420a back in the day, black98dsm is a very knowledgeable guy on the 420a he probably knows a trick or two on that little issue. In the meantime ill dig a bit and see if i can find something.

Yes they are in order for disassembly. Maybe someone worked on it before and didn’t mount the engine correctly. I was working on all the prep work for removing the engine. I removed the intake/exhaust manifolds, fuel rail, removed all wiring harnesses, radiator and coolant lines, fuel and spark plug parts. I made sure to label all the hardware and electrical connections. The timing assembly is the only thing left before I can remove the engine (the motor mounts if needed). I’m thinking i should remove the transmission so it can be easier to work with the engine.

That bracket is a pain to remove with the engine in the car. But it's possible. Done it twice. What I did is put a jack and block of wood on the oil pan and jack the engine up high enough to slide those bolts out. Then it's a matter of wiggling that bracket out. It fits tightly in there.

The oil pan started bending when I tried jacking it up. I used a heavy duty scissor jack with wood that covered a big surface area so the weight wouldn’t be on one spot. I even tried adding a foam mat but it still made it bend. I do have a new oil pan that I can replace the old one with with. I could swap the pans and jack up the engine that way.

 

[97egl]

You may need to pull the bolt on the engine mount that is on the cross member so you can get the engine up higher without applying so much pressure. The oil pan will flex a little if its not already dented.

 

[BLACK'98DSM]

I used a fairly large plywood sheet on mine. You more than likely already have an aftermarket oil pan. They are a thinner sheet metal than the original. Since you're replacing the pan anyway you can ahead and jack from there, unless you feel like you're jeopardizing the bolts. I've seen them break off before, but due to overtorquing not pan pressure.

An engine hoist would work as well if you had one. The hood would need to be removed.

 

[JeffGS-T97]

It doesn't take much to jack a motor i usually use a big punch line it up on the jack base and jack the punch onto a bottom block surface. Here is what i use on mine.

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Never jack against the oil pan. They are designed to be exactly the size they are and some seriously critical parts lie under there as well. Damage the oil pick up and the top of thr motor will starve for oil and the oil won't circulate and get really hot leading to full catastrophic failure. Make sure the motor mount in that area is loose and then raise.

 

[dustyboner]

if you take the 2 bolts out holding this hard line, remove the bolt on the front mount and possibly loosen up the bolt on the back mount (its been too long to remember), you can get the mount bracket bolts out.
you have to get the engine up high enough so the bolt just clears the frame rail. then pull up on the hardlines that are in the way so you can get the head of the bolt between the hardline and frame rail. that will give it just enough clearance to get the bolt to come out of the bracket.

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[BLACK'98DSM]

I just remembered how I got that bolt out last time. The engine doesn't need to come up, it needs to go down. The reason I had a jack under the engine was to take some of the stress off the trans mount and axles and I lowered the engine. You can remove that plastic cover with only 2 bolts and a few plastic clips.

I was having trouble remembering that but I found pictures where I had the passenger side of the engine sitting really low and the timing cover off.

 

[Cypherfox]

I finally have the engine and transmission removed. I was able to lift them both out as one complete assembly. The two bolts that I couldn’t remove at the beginning stayed on the engine. I forgot about them and just focused on the removing everything else. I’m going to secure the engine on a stand soon and hopefully figure out why the spark plug was damaged. Thanks for all the replies.

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[BLACK'98DSM]

Definitely keep us updated. I'm curious what happened inside that cylinder.