Straight Talk - Head Gasket

You shouldn't assume anything. There are curative measures, interim measures, and ineffective measures (a category you left out). Any measure you could take might be any one of those, depending on what the situation actually is.

For an extreme example, depending on whether your symptoms are caused by a damaged head gasket or not, replacing the head gasket would be either a curative measure or a (really expensive and invasive) ineffective one.

Another example, if the symptoms are being caused by a bad spark plug, then replacing that plug is absolutely a curative measure. If not, it's an ineffective one. It's pretty much never an 'interim' one—there's no reason to expect it to slow the progress of some unrelated problem.

Or, you might read often on PriusChat that clogged EGR can cause head gasket damage. If that's so (not all are sure), then cleaning EGR earlier might have been preventive, but if the symptoms now are caused by a damaged head gasket, cleaning EGR now would again be an ineffective measure.

People might do possibly-ineffective measures for other reasons. For example, someone who isn't sure yet what's causing the symptoms might change spark plugs, not thinking of it as an 'interim' measure, but as a diagnostic one: to find something out.

Or someone who thinks the problem really is the head gasket will probably clean the EGR too (not on its own, but in conjunction with fixing the gasket!) in the hope of warding off future failure of the new gasket.

So far, I don't think the symptoms you've reported—two isolated instances of a rough cold start, and a subsequent nice cold start two days later—sound all that alarming. Occasionally, cold starts are rough. Especially if the last drive cycle preceding the cold start was a short one that didn't warm things up much (that's a separate, known gen 3 quirk).

If you are worried nevertheless, and you want to either confirm or rule out a head gasket issue, keep a close watch on the coolant level, and maybe look into obtaining a borescope, one with an extra camera for viewing to the side or back. That seems to be the best-regarded method around here for detecting early signs of a gasket leaking coolant.

 

Don't count on it listen to yourself or. Look at your text the car is your lifeline and so on and so forth well gen3 could not be my lifeline personally. It's a 2z engine same as Corolla most of the differences a meccie wouldn't care about low tension rings etc . So if they can work on a Corolla engine they could work on yours many don't want to because of the hi voltage wiring . Scares folks. Gen3 is known for these antics and yours is 15 or whatever years . Real gamble for a lifeline. And one this old . I've gone it twice with poor outcomes both times . Been driving and working on Toyoda long before they were popular. I wish you luck you will need alot. There was a cottage industry building up around this car and this work none survived . Many wer scams .

 

you can definitively corroborate or eliminate the head gasket with testing. others will advise best practices.
driving it won't hurt anything, definitely keep a close eye on the coolant. you could hook something up to the obd port to which temps.
either it's already blown, or it isn't. if it isn't, there's no way of knowing how long it will last.
proper maintenance before and after you purchased it are important, but 10k oil oil changes and not checking/changing the coolant can be prolematic.
best you can do is clean the egr circuit, do proper maintenance from now on, and either change the hg proactively (if it's not blown) or immediately if it is, before other engine damage is done.

 

10k means 10,000 miles. that's toyotas recommendation and some here feel that it can be part of the hg problem.
same with coolant. some feel toyota rec is way too long, but it should at least be tested for ph, so it doesn't eat the hg.
i'm not saying that you did anything wrong.

 

My comment is supposed to mean just what it says I wouldn't put all my eggs in that basket of a vehicle . I think you're going to get to find out actually good luck to you

 

Well, you'd get that sense reading here, because it has happened to enough people who come and post about it. And some post about shops who replace head gaskets or engines for a lot of gen 3 owners. So it's definitely a problem that crops up in a lot of gen 3s.

By the same token, there were millions of gen 3s made. Lots of them are still running with tens of thousands of miles more than yours and the original head gasket (mine is one, for example).

Like, rip bandaid how? Preemptively replace the head gasket before it fails? Or assume the first two rough starts in your Prius must be a failed head gasket and not any of the other reasons for a couple rough starts, because lots of other people have talked about it? Like, replace the head gasket before determining whether it is or isn't bad?

To me, those ideas sound alarmist.

Poke it into the cylinders through the spark plug holes, put normal pressure (14 psi or so) on the cooling system, and use the lens that can see sideways/up to look for drips of red fluid forming at the top of the cylinder where it meets the head. Reports around here are that gives you a definitive result earlier than other common tests for gasket failure.

I don't think so. Have you ever noticed anything strange about levels, to this point?

 

I don't think, with two mildly rough cold starts and a nice cold start, I would even be spending mental energy on a borescope at this point, unless you enjoy browsing on amazon to see the choices available.

I would just drive the car and keep casual note of how it seems to be acting.

I pop the hood every time I fill up, check the dipstick, and eyeball all the fluid reservoirs. My driver training instructor drilled that into me. Maybe that's a routine you can add?

 

With the gen 3 track record, I'd be getting more "formal". Head gasket always go, and around your miles it's too common. Unless the EGR system has had regular cleanouts.

There's EGR and head gasket links in my signature. The Critic's thread in particular is a good read. (on a phone turn it landscape to see signatures)

 

My 2 cents: Toyota's been less than forthcoming, to put it politely.They did issue a (toothless) Warranty Extension; my Canadian version, essentially saying:

if your car displays DTC P0401 (Diagnostic Trouble Code) or "rough idle and/or tapping sound" at cold start, and has been on the road less than 10 years and/or 240k kms (150k miles), we'll fix it.

It also says, and I would say this is something that could be contested in court:

While the majority of vehicles will not experience this condition:

^ Just thus, underlined and italicized:



If Toyota had made the effort, ran a few test vehicles around a test track for 200k miles, they would have caught this, and the inadequate "low-tension" piston rings (prone to oil consumption). With that amount of miles, the interior of the EGR coolers look thus:



It doesn't take a genius to say "that ain't good". And "what's this thing do, make it ok to run lean?"

 

"Taking care of it" at this juncture is tricky. The car's been run without EGR cleaning for 150k miles, and is "maybe" exhibiting early head gasket demise symptoms. So what to do.

First off, everything EGR was eminently cleanable, no need for replacement. The cleaning could have been DIY'd for about $30~40 USD worth of gaskets and shop supplies, on a weekend. There's a few shops in the States that'll do it thus, for around $600~1000 USD. But that ship has sailed.

The head gasket likely is compromised, and slow but sure starting the leaking. Toyota hasn't really acknowledged that, issued a warranty extension. I'd monitor coolant level, listen for cold-start shake symptoms, and when they happen, verify with borescope, get on head gasket replacement promptly. Use the genuine Toyota gasket kit:

Toyota Genuine Engine Overhaul Gasket Set 04111-37316

And replace the head bolts, for insurance:

Cylinder head bolt: 90910-A2011 (10 reqd) <or 90910-02166 (older, avail on Amayama)

How's the oil consumption?

 

Suggest you keep close eye on coolant level. You can for instance take pictures of the reservoir to help following up. If you’re not loosing any coolant i would not worry too much about the head gasket.

 

I'm with ChapmanF here- learn to read the coolant level and set a habit of checking it each time you get fuel, while you continue to enjoy driving the car.

The symptoms you've described aren't conclusive, not by a long shot. Way too early to spend any real money on this.