"Coolant Leak Detonation"/possible head gasket leak. Time to cut losses?

So a while back I had posted about a check engine light that came on after I picked my car ('09, 76500 miles) up from a recall services (airbag, computer update). Car would shudder and the light would turn on, then would go away by the next day.

Took it in to the dealer, got it scanned. Dealer said cylinder 3 was misfiring, that they moved around the coils, and sent me on my way without charging me a dime.

Fast forward a month, and it happened again. This time, the service rep says that coolant is leaking in, touching the top of the cylinders, and “detonating” (didn’t think engine coolant was flammable). Said the possible cause could be up to a head gasket leak. So far it’s up to $270 for the code scan and compression test, but more tests could be required. So here are my questions: The car’s worth about $6000 according to KBB, choosing the lowest rating, and a head gasket job would cost over $2K. At what point do I cut my losses and sell or trade it in (if a dealership would accept a car with a possible head gasket failure)? What else could it be? How much would I expect to get back in sale value to get some of the other issues fixed (coolant pump could be going bad, broken window clips on one door)?

Would you pay 6000.00 for a vehicle that needs 2000.00 worth of work ? Of course not . Kelly Blue Book is usually higher than what a vehicle is really worth. If you can afford to trade and not upside down on this thing bail just for piece of mind. Other wise fix and drive it into the ground.

Why are you taking your out-of-warranty vehicle to the dealer for repair?

Just from that statement alone, find a good independent shop for repairs now, and in the future.

Something sounds fishy.


The problem I’m referencing (the check engine light) happened immediately after I picked the car up from recall service. As in, right as I was driving it out the service center. I brought it back to them because I suspected it was related to the computer update they installed.

A recall is the only time you bring an out-of-warranty vehicle to the dealer.

Once the recall service is performed, and the vehicle runs fine for a month, and a new problem arises, it’s not covered under the recall.

So, take it to an independent honest shop.


Do you happen to have the 2.4 liter 2AZ-FE engine?

If so, I’ve got some pointers for you

That is sort of a puzzling statement. If coolant leaks into the cylinder I suppose the steam could increase the pressure inside during the compression stroke and cause a detonation effect, meaning the gasoline was exploding too early in the cycle. That could make a detonation-like sound (ping), maybe that is what the tech is hearing.

In any event if the engine is leaking coolant into the combustion chamber, something has to be done pronto. There are various test that can confirm that, but let’s assume that is in fact the case.

hmmm … with only 77K miles on a 09 Matrix, I’d be inclined to just replace the head gasket myself. Did the shop have any theories for why the head gasket failed? It’s pretty uncommon for a head gasket on a Toyota to fail w/that few miles. Did the engine ever have an overheating episode? What I’m getting at is if this was caused by the engine overheating, there may be more problems than just a failed head gasket. But if it just a random head gasket failure, my suggestion is to just pony up the dough and ask your local inde shop to replace it with a new one.

If this is the 2AZ-FE engine, it may be not be so simple as replacing the head gasket . . .

I hope the repair ends up working out and the car lives on. Not very many of those union-built, California NUMMI plant Toyotas left in circulation. I’m with the group. You need a good local mechanic. I’ve saved thousands keeping my '07 Highlander going since I quit on the dealers.

Sadly, I live in an apartment building with assigned, uncovered outdoor parking spaces and no garages/storage units. No place to keep tools nor a space to work on the car. DIYing isn’t an option.

There’s never been an overheating episode, and I’m the original owner. Like I said, the problem started after recall servicing and “complimentary 25-point inspection”. They did say that the water pump was getting loud and should be replaced soon, but that it hadn’t yet failed. That said, the temp gauge was fine.

And thankfully there’s a highly rated mechanic walking distance from my apartment.

What engine do you have?

You haven’t addressed db4690’s question about the engine number in your Matrix OP. If you don’t know the engine number, you can find it by popping the hood. There’s a decal pasted under the hood that has EPA required emissions info on it, and it also has the engine number. The 09 Matrix came two engine options, a 2.4L 2AZ-FE or a 1.8 L 2ZR-FE from what I can see.

It’s the base model, so it’s the 1.8L.

Anyway, the techs came back and said it passed the compression test, and the real problem was almost certainly a bad ignition coil (they can’t be 100% since they weren’t able to reproduce the misfire in the shop), but that most of the other symptoms described fit with the car’s computer losing all of its operating parameters during the update.

First time I brought it in after the problem showed up, they couldn’t find a root cause, so they moved the coils around to see if that would solve it. Sure enough, the cylinder that was misfiring changed, but the specific coil was the same. Thankfully the difference between yesterday and today was that yesterday’s service rep was out, so a new guy came took over and looked at the reports from the previous appointments.

Coil failures are not unusual. Seems like a good idea to wait for the diagnoses to be completed before considering to replace the car. When problems are difficult to replicate and the phone keeps ringing, service advisors sometimes mention all sorts of failures that might be possible.