Early Model LC200 Head Gasket

[alexvallorosi]

Hey guys,

Has anyone attempted a repair after a head gasket failure on an early model 200 series? I was adding a little bit of coolant at every oil change and then intermittent P0308 which is now consistent after a few miles. After a cooling system pressure test (doesn't hold pressure) and bore scope inspection of cylinder 8, there is indeed coolant in there. I suspect a cracked block or head gasket failure. I'm thinking of tearing down the top end, getting it resurfaced and replacing the HG.

Anything in particular to look out for when performing this job? I know this is a pretty rare failure on these motors.

Thanks all!

 

[alexvallorosi]

So far I got the intake off. I took it out in one piece but I guess it splits into upper and lower like the old 5VZ motor. Valve covers next then onto the heads. Just trying to see if I’m dealing with a cracked block or not.

 

[alexvallorosi]

Just doing some inspection here, firstly I cleared away quite the rats nest under the intake. I noticed that the valley plate was leaking quite a bit from this area as well. The rats chewed on my knock sensor wiring but not completely through it.

It sounds like the valley plate leakage is a pretty common issue with these motors and it makes me wonder if the coolant buildup in this location is what compromised the head gasket.

 

[alexvallorosi]

A little more progress tonight. Got a bunch of the frustrating things stripped out of the way so that I have more room for access. Radiator, fan, and shroud off. Fuel rails off. Most of the cooling system that wraps around the passenger valve cover removed (a couple stainless hard lines and a bunch of hoses). Most of the wiring harness unclipped.

With all of that out of the way I was able to pull off the passenger valve cover. I was very happy to find that it looks super clean, no varnish, and the part of the cams that is showing looks great - totally undamaged. Really trying to take my time, label things, keep track of bolts, so that I know how everything goes back together.

Next up is the driver valve cover, accessories, front cover, cam tower, then I'll be at the heads. Does anyone know the loosening order for the cam cradles and/or the cam tower itself? I'm getting close to the point where I have no idea what I'm doing.

 

[alexvallorosi]

I pulled the DS valve cover while I had a chance before dinner tonight. Same story here, exposed cam lobes are in outstanding shape. The whole thing looks very nice and clean. There is more varnish under the driver side front cover near the timing chains than anywhere else I have seen in the motor so far.

 

[alexvallorosi]

Got a couple more components stripped off tonight. Secondary air system off the top and the tensioner pulley and part of the water pump off the front.

Underneath the secondary air system you can really see the extent of the damage from the valley plate leak. I'm pretty confident at this point that this is the source of the compromised head gasket, from coolant leaking in this position.

I'll also check the knock sensors for resistance as this one in particular is pretty fouled up from coolant.

I'm keeping a running list of replacement items as I encounter them in the process. Please feel free to let me know if I'm missing anything or if you have any recommendations:

Definitely Replace
Coolant Crossover Pipe Gaskets
Valve Cover Seals
Valley Plate Gasket
Timing Chain Tensioners
Head Bolts
Little gaskets on the secondary air system pipes

Probably Replace
Chain Guides?
Timing Chain?
Cam Phasers?
Valve Springs?

 

[linuxgod]

If you hadn’t borescoped cylinder 8 I would’ve assumed your coolant leak was the valley plate as that’s pretty common. But if you see coolant in #8 then it seems very possible that’s an issue. I would think a couple people (maybe @Atwalz thread?) have had this and have photographed where the head gasket gave out… iirc there’s a small cooling passage and the HG is thin there.

Knock sensor wiring harness is cheap. Replace it if compromised. A mouse had chewed mine, which was discovered when the valley plate leak was repaired.

Not sure your mileage but if the heads are coming off then you’ve got the front of the motor open so I’d 100% do the timing chain tensioners (or at least the drivers side) as a PM since they often get rattly.

Again not sure your mileage but a few people have started seeing heater hose T’s giving out at the 200k+ point so you might consider them if they’re easily accessible now and you’re st higher mileage

I don’t think the timing chain is necessary. Similarly a few people have seen issues with valve springs but it’s really rare ultimately and I suspect the cost and effort to replace all of them will be quite a bit.

 

[alexvallorosi]

If you hadn’t borescoped cylinder 8 I would’ve assumed your coolant leak was the valley plate as that’s pretty common. But if you see coolant in #8 then it seems very possible that’s an issue. I would think a couple people (maybe @Atwalz thread?) have had this and have photographed where the head gasket gave out… iirc there’s a small cooling passage and the HG is thin there.

Knock sensor wiring harness is cheap. Replace it if compromised. A mouse had chewed mine, which was discovered when the valley plate leak was repaired.

Not sure your mileage but if the heads are coming off then you’ve got the front of the motor open so I’d 100% do the timing chain tensioners (or at least the drivers side) as a PM since they often get rattly.

Again not sure your mileage but a few people have started seeing heater hose T’s giving out at the 200k+ point so you might consider them if they’re easily accessible now and you’re st higher mileage

I don’t think the timing chain is necessary. Similarly a few people have seen issues with valve springs but it’s really rare ultimately and I suspect the cost and effort to replace all of them will be quite a bit.

Thanks for the tip. Mileage is 239,000. The shop that did the cooling system pressure test did bore scope the cylinder to find coolant. I did borrow a bore scope and double checked the work and found the same but did not get a good photo of it.

I’ll add the knock sensor harness to the list and might as well do the heater T’s while I’m here. Timing chain tensioners are a definite, what do you think about the chain guides? I feel like I should probably replace them.

 

[alexvallorosi]

A bit more progress tonight. Got the power steering pump, alternator, and a/c compressor off the motor. A few more accessories to handle tomorrow, fan thing, oil filter/pump thing, water pump, idler pulley, and then we should be about ready to pull the timing cover off. Then beyond that it's really just down to pulling the cam towers and the heads. I will say I thought the alternator was a bit of a challenge until I attempted the a/c compressor. That was quite difficult. You have to properly vent the lines in accordance with EPA regulation and then get at each of three mounting bolts and then one nut/stud combo. With the KDSS lines in the way it's not an easy task.

 

[linuxgod]

Thanks for the tip. Mileage is 239,000. The shop that did the cooling system pressure test did bore scope the cylinder to find coolant. I did borrow a bore scope and double checked the work and found the same but did not get a good photo of it.

I’ll add the knock sensor harness to the list and might as well do the heater T’s while I’m here. Timing chain tensioners are a definite, what do you think about the chain guides? I feel like I should probably replace them.

I’m not sure if they contribute to the rattling we get? If the cost is low it probably won’t hurt. Anything which avoids removing the timing chain cover in the future is a win in my book if it’s not expensive.

 

[bloc]

Guides are cheap insurance.

 

[alexvallorosi]

Guides are cheap insurance.

It's settled then, they'll be replaced. Going to make some more progress tonight and I will publish another update when I do

 

[alexvallorosi]

A bit more progress today. Got the oil pump/filter assembly, idler pulley, fan thing, and water pump off. I pulled the crankshaft pulley bolt out but I might need to use a puller for the actual pulley as it’s pretty stuck on there. It’s sitting with a drop of WD40 on it right now so hopefully that frees it up. Once I get this timing cover off should I be putting timing marks on the cam phasers and everything? Does anyone know how to do that? Or does it all line up and time pretty easy after?

 

[alexvallorosi]

Timing cover off. I definitely missed a bolt or two when removing it. If you’re attempting this job for yourself I would say just take your time and find all the 12 and 14 mm bolts (there are a lot of them) so that you’re not prying on a timing cover that is still bolted down. And pry gently. Also would probably recommend taking the valley plate off and pulling the coolant pipe through from the back, the timing cover was definitely hung up on the o-ring on this pipe.

Here is what my replacement parts list is looking like so far:

Definitely Replace
Coolant Crossover Pipe Gaskets
Valve Cover Seals
Valley Plate Gasket
Timing Chain Tensioners
Head Bolts
Little gaskets on the secondary air system pipes
Heater T’s
Fuel Injector Gaskets/O-Rings
5W30 Motor Oil
Drive Belt
Hood struts
Chain Guides

Probably Replace
Timing Chain?
Cam Phasers?
Valve Springs?
Radiator?
Water Pump?
High Output Alternator?

I am going to start putting Toyota part numbers to these

 

[linuxgod]

At 239k yes I’d do the water pump, thermostat, and hoses. Toyota says the clamps are single use so probably wise to do them. Radiator is optional if the top is in good shape… at 239k it’s likely been done but if it has the square edge spot at the top rather than the new rounded one it’s probably a good time to swap it.

If your starter hasn’t been replaced, this might be a time to do it if the exhaust manifold is off. They’re a PITFA to get out and it’s not normally a “while you’re in there” kind of job but if you have the heads coming off I’d consider it given your mileage.

 

[alexvallorosi]

Well…. This wasn’t in the cards for today.. or really ever. Progress temporarily halted until this blows over. Hoping the tent and towels keep the water off of the exposed valves, timing system, etc.

 

[prwillard2]

View attachment 3677647

Well…. This wasn’t in the cards for today.. or really ever. Progress temporarily halted until this blows over. Hoping the tent and towels keep the water off of the exposed valves, timing system, etc.

Dude this weather here right now is crazy. Hoping things stay dry for you.

Let me know if you need help

 

[alexvallorosi]

Dude this weather here right now is crazy. Hoping things stay dry for you.

Let me know if you need help

Thank you! As you know this isn’t very common in 29 Palms. Maybe a couple times a year, but when it does rain it pours.

Despite my best efforts to secure it, the tent came down. I stuffed a lot of towels in anywhere I felt like water could get in. The engine bay was very dry after things passed over. I’ll still probably treat the timing and valves with some oil anyway on account of the humidity just to be safe. And I’ll continue working in the evenings this coming week.

In the meantime, as soon as weather passed, I had to act quick on my freshly sandblasted stock tank pool and apply a white vinegar treatment and coat it with an epoxy paint. Not sure if anyone cares but I thought it looks pretty good.

 

[alexvallorosi]

Quick update! I was able to pull the passenger cam tower today after a bit of time off. It was pretty quick work. Cylinder head is next but I have to pull the exhaust manifold first. I had a thought, but I’d like to hear what you guys have to say - if the problem only exists on the passenger side, is there any point to machining the driver side cylinder head? My gut says yes but also if it ain’t broke… why split the cylinder head from the block if I don’t have to…

 

[Sandroad]

Nice work so far. Reminds me of doing the HG on my 80. If it was mine, I would not pull the DS head. The internals look amazing for 239k miles. I don’t know about head weight on the 5.7, but consider that you may need help lifting it out.