83 Supra Beast !! 454 engine over heated, now ticking- Help!

[DAFF]

Wonder if a lifter collapsed from the heat. Would explain why you cant adjust the tick away.

[92SupraComp]

Fresh water cooling isn't pressurized, so, at 212 water starts to boil...

[cadunkle]

Sure pretty much all of them.

Typical thermostats are 190-205*F on modern cars. This sets the minimum operating temps. On a hot day under load you could easily end up higher. A typical 50/50 water antifreeze mix and typical system pressure around 15psi will be stable up to 250*F. At that temp you should not be doing any damage to anything, its not as ideal as running at 200 but still should not cause any serious issues.

Then name a few engines, specifically, that normally run at 220*-230*, I'd like to verify this because I don't believe it for a second and I don't think you're basing your statement on any facts.

An engine with a 195* thermostat should run around that temperature and not see beyond 10*-15* worst case coolant temps above thermostat temperature and even then only when working very hard in a hot environment. 25*-35* or more above thermostat temp is indicating of an insufficient, worn out, or damaged cooling system. Some newer engines use an electronically controlled thermostat, to regulate the temperature. If it's one of these engines you're talking about, please specify which one and at what temp it's designed to run, at what temp the computer fully opens the thermostat. I guarantee you the thermostat is fully opened before 230* and the engine is not designed or intended to run 230* or more.

230* is generally accepted as the temperature at which engine damage begins. Claiming anything up to 250* is not damaging anything is simply not true and could give some people here a false sense of security and result in severe engine damage as they may believe your claim that 230* or even 250* is alright. When engine temperatures get too high, generally a coolant temp around 230*, damage is likely to occur. This is primarily from expansion of metal. As the temperature of metal increases is expands. When different types of metals are used in engines there may be different expansion rates, such as a cast iron block and aluminum piston.

Aluminum expands more than cast iron over a given temperature rise. Piston to cylinder wall clearance decreases during an overheat and the result is heavily scuffed pistons which will develop deep grooves vertically in the piston and damage the cylinder wall similarly but to a lesser extend as aluminum is the softer material. Ring lands can also be damaged, becoming distorted or clogged with pieces or metal scraped off the piston skirt or cylinder wall. The rings then cannot move freely and loss of compression follows. Extreme heat will also damage the rings in that they lose tension, so even if the ring lands are not damaged resulting in stuck rings, the rings will not seal as well. Loss of compression and excessive oil consumption is the result. Blow by will of course increase as well. Any engine designed to run 250* coolant temps will have significantly larger piston to wall clearance than an engine designed to run in the 180*-210* range, which would cause quite a racket on a cold start and until up to temperature.

Another common issue at temperature nears or exceeds 230* is head gasket failure. This again occurs from expansion of metals. Both the block and the head expand as the engine gets hotter. This expansion needs to go somewhere, so several things or some combination can occur. The heads are securely bolted to the block, with a gasket between them. As the block and heads expand the head gasket will be compressed further as it is softer than the block and heads and made to compress to a certain working range (this is why we torque head bolts or studs). If it is compressed too much it may not recover once the engine has cooled. The head bolts will also have to hold more pressure and may stretch, deform, or in extreme cases break. The head of block mating surfaces may also warp, the fewer head bolts and larger the spacing the more likely this is. This is also more likely with aluminum heads on an iron block. The result is a failed and leaking head gasket.

There are other failures and damage that can occur as well. Oil temp increases thinning the oil, breaking down or coking the oil at particularly high temps and resulting in bearing damage or damage anywhere there is potential metal to metal contact. If the coolant boils over localized hot spots will occur where the coolant is no longer in liquid form and thus cannot effectively transfer heat. This is more likely in marine applications with raw water cooling as our coolant boils at 212*, period. This will increase the likelihood of warping in any area the coolant boils.

I'd just like some information I can verify on your 220*-230* design engines and that 250* is A-ok. All of what I've said has been common knowledge for decades and easily verifiable with a quick search. Beyond that, a new car engine designed to run around 200* like many new cars is very different from a 50 year old V8 raw water cooled in a boat. Different engine design, different gasket, different design temps, different clearances, etc. The farther you take an engine outside of its design temp the more likely damage will be, as clearances, gaskets, and clamping design are all made for the intended use and conditions.

The OP has stated in addition to his ticking noise from #7 valvetrain it's also down significantly on power. If it is not an obvious misfire from #7 or any other single cylinder but has lost a lot of power I'd suspect fairly uniform piston or cylinder wall damage affecting ring sealing ability, which is why I suggested doing a compression test. This would be especially useful and meaningful since he has done a compression test at some point prior to the overheat when it was running well so he can compare numbers.

[michael hunter]

I think you are confusing normal operating temperature with engine damage temperature. Most autos today will fluctuate between 200-220 depending on if its moving or if the fans are running. Anything over 230 I would conciser overheating but not necessarily engine damaging.
The engine we are talking about here is a 83 454 I don't think you will find any aluminum components in it. As I said before the rubber hoses on the exhaust and manifolds would be destroyed before engine damage would occur unless it was ready to go anyway . I still think he has a bad lifter but without seeing and testing myself its only a guess?

[cadunkle]

No, I am not. If you look at my second post in this thread I clearly stated:

It got at least how hot? 230* is where damage starts to happen.

I don't believe any normal automotive engine these days, or ever, is intended to run at 230*. 230* is where damage from voerheating generally begins. That's not a hard limit, but give or take a small amount depending on the engine design, clearances, type of failure causing to to get that hot, etc... Bottom line is you don't want your engine getting up past 230*. If an engine with a 195* thermostat is running at 220* it has either a damaged, worn out, or inadequate cooling system. With a 195* stat I would consider 190*-210* to be the expected operating range with an appropriate cooling system

You stated:

Most auto engines today run normally at 220-230 I doubt you caused any internal damage to the engine without melting the rubber hoses first

I don't believe your statement, 230* is just too hot to reliably run day in day out. There will be rapid wear and at those temps there isn't much safety margin even for an engine with larger clearances to account for that design temp. Particularly with aluminum heads and even blocks there is a lot more expansion, compressing and stressing the head gasket quite a bit. Every small increase in temperature means the head gasket is getting worked harder, crushing further and must be able to be resilient to this extreme cycling. What type of head gaskets are used in these engines you won't specify to withstand this?

Good point about the hoses, but the OP never mentioned melted, deformed, or leaking hoses. It's absolutely something to check after any overheat of a marine engine. He didn't say anything about them so my assumption is he did not check and they're probably not totally gone or he would have noticed. The OP did mention it got hot enough to smell, though he did not say what it smelled like. It could well have smelled like burning exhaust hose, among other things, but we don't know as he did not say what it smelled like or indicate anything either positive or negative about the condition of the exhaust hoses.

A typical 50/50 water antifreeze mix and typical system pressure around 15psi will be stable up to 250*F. At that temp you should not be doing any damage to anything, its not as ideal as running at 200 but still should not cause any serious issues.

Sorry bud, 230* is playing with fire and you might get lucky, but at 250* the damage is done. Your pistons are damaged and you've likely got head gasket issues and warped mating surfaces at a minimum. You're beyond running large piston to wall clearances to account for expansion because the block and head surfaces and subsequent abuse on the head gasket is going to result in failure. To take that type of abuse requires at least a better grade of metal, thicker deck castings, and more fasteners preferably large studs. I don't believe it's economical to build an engine to take those temps for your typical new cookie cutter econobox or to risk the warranty claims, so I'm highly skeptical of any claim that new engines normally run at 230*.

The engine we are talking about here is a 83 454 I don't think you will find any aluminum components in it. ... I still think he has a bad lifter but without seeing and testing myself its only a guess?

Pistons are aluminum. We are talking about piston damage and ring failure, at least I am suspecting that is what has happened. I may be right or wrong, but the OPs provided information supports my theory. It would not surprise me if he has a damaged lifter, as he clearly has some valve train problem on #7 from his description. Compression test and inspection of the suspect lifter are his next best course of action, to determine whether he needs to pull the engine and rebuild or if he can get away with less than that.

[CJD]

I've got a 2004 Range Rover that does have a 230 degree thermostat. It takes a special electrically heated thermostat that begins to open if you add throttle to prevent boil over. It's a rather complicated cooling system, and it would not work with plain water like our boats use. A fresh water cooled motor will naturally have to use a lower temp thermostat.

A ticking could be anything from a spun bearing to a stuck valve. A flat lifter could still be adjusted to zero lash to eliminate the ticking...just like adjusting a solid lifter...so I doubt it's a lifter.

[michael hunter]

My experience is mostly with GM engines. Most cooling fans don't come on until the mid 220s . I still don't see the engine damage at 230 but I'm no Mechanic anymore. I was one in 83 and it would take a lot more than 230 or even 250 to melt a piston or deform the rings. . Without knowing how hot it got its anyone's guess what damage has been done. So I'm afraid we will have to agree to disagree on this one . I always take the easy fix first until its proved to go further if it were my engine I would still be looking at the lifter.

[richard.tobian]

most likely need to reset the rocker arms, they come loose at times. good luck

[8509kmv]

I had the same issue last year luckily it was just a rocker arm adjustment. They had some excess play. Check you hydraulic lifters before to adjust the rocker arms just to make sure they didn't get any bad wear on the bottom. PM me if you need the adjustment operation.

[cadunkle]

It would be good to read the OPs posts before commenting. OP has already identified the noisy valve and tried adjusting. Increasing preload enough to quiet down the noise results in a misfire from the valve not closing.

I did take the cover off and it sounds like the ticking is coming from the rear passenger cylinder. I tried to adjust the valve lash and in order to stop the ticking, i have to tighten the bolt so much it makes the engine run rough.

This noise could be cam or lifter damage, valve or guide damage, rocker damage... Anything like that. Only way to find out is to start pulling those components apart and see what doesn't look right. I'm anxious to see an update on the cause of the noisy valve along with compression numbers before and after the overheat.