3400 head gasket destruction

[AaronGTR]

Hey guys. Been a while since I posted any updates on my build in here, so I'll get up to date first.

Fixed a bunch of issues I had with the belt, tensioner, and alternator, and ended up getting more boost. 9.5psi @ 6400rpm with a 2.2" pulley. Also installed a 2bar MAP and got that working so I could log the boost level. I dyno'd the car a couple weeks ago and ended up making 320whp and 300 ft/lbs on the last pull with the exhaust cutout open.



Injectors were hitting 21ms pulse width from 5600rpm up and AFR's went from 11.6 to 12.6 in the last 1000rpm to redline, so I figure the injectors are maxed again. Guess I should have kept the Lucas 42's I had. Anyway IAT's where getting in the 90-100 degree range at full boost and removing timing wasn't helping anymore. Really need an I/C or alky spray to cool it off, but I figured I'd throw a few gallons of race gas in it or drop the redline a bit to control the KR and take it to the track to see what it would do.

First run was a new PR of 13.788 @ 103.73 mph, with wheel spin off the line, and it seemed to be hitting the rev limiter on the shifts. Second run I feathered it off the line and hooked better, and it seemed to shift better. 1/8 time and speed looked on pace to hit a 13.6 maybe, but right after the shift into third something let go. Engine started sputtering and huge cloud of white smoke out the back. Still ran a 13.8 but only at 96 mph. Got to the end of the run off and turned into the return lane and the engine died. Low coolant light was on. Coasted off into the grass and stopped. The PCV valve had been blown out of the valve cover and blew oil/coolant up on the hood, and there was coolant pouring out of my exhaust cutout!

[AaronGTR]

Onto the carnage. Tore the engine down yesterday and found both head gaskets had blown out on cylinders 3 and 4 between the coolant passages, right into the lifter valley. I'm assuming that somehow either the compression from the pistons or the SC pressurized it all and forced it up into the heads and through the PCV lines because there was coolant in my intake, in the supercharger, the intake manifold, the intake ports in the heads, combustion chambers, and the header primaries.









Question is, do you guys think the coolant going through there may have damaged the rod bearings or bent a rod? Or should I be ok to try just rebuilding it with new head gaskets and running it? Also all the piston tops looked clean except for #2 which has some carbon on it. Someone told me burning coolant will clean the pistons off like that, but why would #2 still be dirty then? Do you think maybe that piston may have a bad oil ring or something? I've never done a compression test on the engine. Wishing I had now before it blew.



Also found one other weird thing. The exhaust valve push rod on #3 was worn on the end that sits in the lifter. It got worn down into kind of a cone shape but on an off angle from center, so that the oil holes weren't lined up and it formed a little knob that was probably blocking the oil hole in the lifter. Any ideas what might have caused that? Maybe a bad lifter or something? Or Spring bind maybe? I have no clue at this point. The holes in the push rods are a little smaller than the stock ones, but the guy at Smith Brothers told me that wouldn't matter since they would still be exposed to the cup in the lifter for oil flow. I'm wondering if maybe I shouldn't drill a chamfer into the ends of them or something though? Don't know what to do at this point but I need another push rod and and don't want any more to fail like that.

quick correction: that push rod was for the cylinder #5 exhaust valve. I double checked it and found wear in the cup on that lifter. Guess I'll need at least one new lifter. Or maybe I should replace or rebuild all of them? Anyone think it might be an oiling issue with the bigger cam and stiffer valve springs... perhaps the LS lifter springs might help? I don't really know what their function is or how they change the lifter operation.

[02GT_Skyhigh]

Ouch. Pressurized coolant blowing throughout your motor....
You cant plan on something like that happening.
Do you think that happened to the push-rod from Wot to engine dead?
Could have been worse if you weigh it all out... Best of luck with the carnage

[bob442]

looks like debris got into the lifter area and wore down that push rod. tearing down the motor wont hurt to check rods and bearings, if its all good then you can just slap it back together, if not, you'll be glad you tore into it. There is a posibility that you could have slightly hydrolocked that cyl. but i think you might have had more carnage then.

Guess your looking at MLS gaskets now haha

[AaronGTR]

Hmm... well the only problem is, I don't have any way to pull the engine and tear it apart right now. I have a garage but no hoist, and no cheap or easy way to get one here (or much space for that matter). Plus money is tight. I'm supposed to be moving next month and was also planning on selling my grand prix and making this car my daily driver again. I have a set of MLS head gaskets (the original ones Ben had made) but they are for the 3500 bore. I had originally planned on building the internals and having it bored out and using the 3500 MLS gaskets and 3500 heads. I don't have the time or money for that right now though, so if I have to just get it on the road I'll probably just buy a used 3400 to drop in. I'm just wondering if I can get a new push rod and put it back together as is though and see if it runs, or if it's likely that there is other damage. I don't want to put new gaskets in and put it all together just to start it and find it has bent rods or the bearings are shot or something.

[bob442]

well if you have a bent rod, you could always measure with a dial gauge and TDC on a clean spot of each piston, that way its a decent guess, and if its a bad bearing you will hear it for a while before it goes tits up.

[AaronGTR]

Update:
After talking to several people I decided to also rebuild the lifters with the LS lifter springs. My dad has a '96 vette with the LT4 option. He said the lifters are exactly the same as the LT1 lifters, except for stiffer springs inside to allow the LT4 a higher redline, and because the LT4 has a bigger cam. Seems like upgrading the lifter springs is a good idea with a bigger cam and higher rpm.

Also WOT tech only recommends the LS6 valve springs for up to .51" lift, and my cam is .515" intake and .526" exhaust. Ben told me once they might work now, but could cause problems later. They didn't hit full spring bind, but the top couple coils did touch when I checked them, and after some research it seems like that can cause the springs to do funny things at certain rpm and ruin valve train harmonics and control. So I'm thinking either upgrade to the comp 26986 springs, or get a cam that I can use with the LS6 springs.

Biggest problem though I think IS the billet cam. I now have definite proof that it DOES wear the oil pump drive gear. Thank you Milzy for telling me that before I bought it and installed it. Here is one side of my gear. You can see some wear on the face.



And here is the other side. You can see how thin the teeth are on this side, and you can see the edge of the groove the cam gear has carved in the face of the teeth. This was after only 12,500 miles in the engine.



This is probably where the high iron in both my oil tests came from. The cam is billet steel and the oil pump gear is cast iron so it is going to wear first. Of course I can replace it with a bronze gear which is softer metal and won't wear out the other engine components, but they burn up too fast and have to be replaced constantly. The iron gear will last longer, but the iron in the oil will cause wear. So basically the cam may have contributed to the other failures... I can't be 100% sure... but if I want my engine to last it needs to come out. So looks like I have to find a way to pull the engine now. Great.

Basically I'm going to address every possible issue at once, right now so that I can make this thing reliable enough to daily drive again. New lifter and push rod, LS lifter springs, maybe new valve springs maybe not, definitely a different cam, and probably a 94-98 timing set. Guess I need to talk to Ben about cam profiles. And I need to find a hoist and a way to get it to my house. Fun.

[bszopi]

Ouch. Glad you posted this over here, as I was following up over on GAGT, but I can't post over there any more...

Banned!

Anyway, where in FL are you now? Since Ben is down there now, might be worth it to visit him, if he's close that is...

[MilzyZ34]

Update:
After talking to several people I decided to also rebuild the lifters with the LS lifter springs. My dad has a '96 vette with the LT4 option. He said the lifters are exactly the same as the LT1 lifters, except for stiffer springs inside to allow the LT4 a higher redline, and because the LT4 has a bigger cam. Seems like upgrading the lifter springs is a good idea with a bigger cam and higher rpm.

Also WOT tech only recommends the LS6 valve springs for up to .51" lift, and my cam is .515" intake and .526" exhaust. Ben told me once they might work now, but could cause problems later. They didn't hit full spring bind, but the top couple coils did touch when I checked them, and after some research it seems like that can cause the springs to do funny things at certain rpm and ruin valve train harmonics and control. So I'm thinking either upgrade to the comp 26986 springs, or get a cam that I can use with the LS6 springs.

Biggest problem though I think IS the billet cam. I now have definite proof that it DOES wear the oil pump drive gear. Thank you Milzy for telling me that before I bought it and installed it. Here is one side of my gear. You can see some wear on the face.



And here is the other side. You can see how thin the teeth are on this side, and you can see the edge of the groove the cam gear has carved in the face of the teeth. This was after only 12,500 miles in the engine.



This is probably where the high iron in both my oil tests came from. The cam is billet steel and the oil pump gear is cast iron so it is going to wear first. Of course I can replace it with a bronze gear which is softer metal and won't wear out the other engine components, but they burn up too fast and have to be replaced constantly. The iron gear will last longer, but the iron in the oil will cause wear. So basically the cam may have contributed to the other failures... I can't be 100% sure... but if I want my engine to last it needs to come out. So looks like I have to find a way to pull the engine now. Great.

Basically I'm going to address every possible issue at once, right now so that I can make this thing reliable enough to daily drive again. New lifter and push rod, LS lifter springs, maybe new valve springs maybe not, definitely a different cam, and probably a 94-98 timing set. Guess I need to talk to Ben about cam profiles. And I need to find a hoist and a way to get it to my house. Fun.

I told you it wouldn't wear out the bronze gear because we did testing about 3 or 4 years ago when we had Tim Kaczun's car come in from canada and decided to tear down some of the engine to check out the longevity of the parts since he had managed to put over 100,000 miles on his stage 2 setup since we installed it. We took pictures of a 7k stock, an ~80-100k stock (i forget), and Tim's oil pump drive, and then we went so far as to send them to a gear manufacturer to have them tested for wear since they have the proper equipment to measure the slop if there is any. Everything turned out good, and there was no excessive wear. You can probably find a post about this on grandamgt.com. als Marc from TCE was involved with helping to get some of the testing done, so he also can vouch for that. If I had to guess what happened with yours, I'd say that your gear was not of the same hardness that Tim's was. When I modify transmission gears for the 4t65e, i find that some gears are not hard to drill into, and some the drill WILL NOT cut. Perhaps the oil pump drive gears have the same variance in hardness?

so i'm sorry to see your oil pump gear has that kind of wear, but that engine didn't fail due to oil pressure loss or a spun bearing. by the looks of your dyno chart and what happened, it went very lean. That blue pass on the dyno is right about 13.3:1 at the end, and being that the car was dyno'd on a dynojet, there's going to be more load on it on the street or track, and could go even leaner. sorry for your bad luck the other day. it's unfortunate, but it is part of this hobby we all have. good luck with everything, and I hope your car goes on to run some really good times.

[SappySE107]

I am sure you meant to say stock gear, not bronze gear.

[AaronGTR]

Yeah, I recall someone posting on here that they used a bronze gear with the billet cam and it wore out even faster. Also my AFR on the dyno pull was 12.6. I have a wideband in my car that is datalogged on my DHP. The failure was not caused by going lean. The run where the gaskets blew, there wasn't even any KR. So in the end I don't know exactly what caused the head gasket failure. I DO know that the cam is destroying my oil pump drive gear and eventually it will fail because of the cam. I also know that iron particles in the oil can lead to other failures and may have had some influence on the lifter/pushrod failure. Bottom line is, if I want longevity out of the engine, I'm NOT going to get it with that POS billet cam.

[pocket-rocket]

It makes you wonder what the V8 guys are doing so they get thousands of reliable miles out of their cams, ect.

[CNCguy]

I can vouch for what Mike is saying about the drive gear from Tim's engine. I sent three gears to my gear cutter for inspection. One was from an extremely low mileage stock engine, the second was from a high mileage stock engine and the final one was from Tim's engine. I don't remember the exact numbers but the gear cutter told me that there was minimal wear difference between the two high mileage gears. It wasn't long before then that I found that the material used in the assembled cams was similar to that used in billet cams and the manufacturers were using melonized gears for longevity which was surprising as in the old days you had to run a bronze gear on a steel (billet) camshaft. The bronze gear was basically a sacrificial part. It would wear first before the teeth on the cam and was cheaper and easier to replace.

With that being said, the uneven wear of the gear may be due to one of the gears not being concentric with the center of rotation. I would securely mount the drive housing and spin the gear to see if it runs out. If it looks good, I would then check the gear on the cam to insure it runs true before putting everything back together. Getting an indicator inside the block to check concentricity of the cam gear will be tricky.

[AaronGTR]

I don't have any dial indicators, so that would be very tricky indeed.

At 46k miles with the stock cam though, the gear showed no abnormal wear. At 5k with the cam, it was starting to show signs of wear. At 12.5k with the cam, it's extremely worn. It's not hard to tell where the problem is using process of elimination.

Simply put though... I am not an engine builder. I don't own a shop. I am knowledgeable enough to install the part myself, but I am not a trained machinist. I don't have the time, tools, contacts, and resources to check those kinds of things. After paying $400+ for a part from a supplier though it's reasonable to expect the part to work without me having to do all that. That is the suppliers job to make sure the part is correct and will work without destroying my engine.

[bszopi]

Aaron, I'm assuming you don't plan on re-using the cam? And its obvious the drive gear is toast. With that said, I for one would be interested in having you send the 2 parts to Marc (if he's willing), and have him take them to his gear cutter for an analysis. With the 2 pieces in hand, the machinist could possibly explain what the issue/cause was. I'd be willing to fit the bill for the shipping if all parties would be interested.