Car:

1998 175K miles, 2.7L Manual

Backstory:

-Check Engine light went on a year ago. P0303. Had Fuel Injectors cleaned at shop. New spark plugs.
-Check Engine light went on 6 months ago. P0303. Had Fuel Injectors cleaned again at shop.
-Check Engine light went on last week. P0303 and P0300. Lost Compression on Cylinder 3 and 4.

Questions
1. Shop claims that the cylinders were totally fine previously when I took it in. Does that check out with you all? I just want to make sure I'm not being taken advantage of here.

2. I can either drop $3K to do a "cylinder head gasket, cylinder head bolt set" repair, or I can just call it quits with the vehicle and move on. My concern is that I drop $3K now, and then next year, I drop another $3K. Should I look at getting a used motor put in? I'm open to all options and suggestions here.

FWIW, I do have sentimental value attached to this car (I've had it for 15+ years)...but I just want to know what the experts on this forum would do. I am in California in case that detail is relevant in any way.

To answer the question "repair or move on". I'd say definitely repair. That's assuming it's not a total rust bucket. Is this a reputable shop? I find it a little odd that the shop cleaned your injectors twice in 6 months trying to fix the same problem.

Get a print out of the compression in each cylinder. The shop just saying "compression loss" isn't helpful or sounding very honest. They are just charging $3,000 for a head gasket job which is not worth it, even for CA standards. If they won't give you more information take it to another shop for a second opinion.

Not saying this is what's wrong but I bought a 4Runner years back for $1700 that had a quote from the shop saying "needs engine replacement" and had multiple CEL codes and was leaking coolant. After changing the spark plugs, replacing the leaking water pump and a good cleaning and wax, I sold it a few months later for $4200. No codes, perfect compression. I would get a second opinion before paying $3000.

Here's my take if your compression truly is bad in both those cylinders. The shop doing the job didn't properly diagnose the cause of the misfire in the first place. They GUESSED it was a fuel injector issue, when all along it was a compression issue. You don't just all of a sudden lose compression on two cylinders.

But, I agree with @gamefreakgc . Get the compression numbers from the original shop and maybe even bring it to another shop for a compression test to confirm the findings. At this point, I'd have very little trust in that original shop. The 3RZ engine is known to burn up valves because the valve lash gets too tight.

I agree with above. SO I assume you dont turn any wrenches yourself, otherwise I would do a compression and leak down test, if it is truly 2 dead holes, I would do the head gaskets etc myself
that 4 banger is a pretty easy engine to work on.

Kong, I dont know if this helps, but i had "lean cylinders" which ended up being a head gasket leak. THis is a 5VZ. My issue was that the engine had 275K on it and was running dirty ( fresh oil got black real quick) from poor cylinder seal as well.

I elected to replace the engine with a reman from gearhead ( LKQ). The cost was $3600 but i havent yet fired it up! Its is NOT an easy job to swap engine given that wiring harness, but they maybe would charge 2K for a engine R&R.

3K for cylinder head rebuild and new gasket seems reasonable actually. However, my point is that if the bottom end ( ring) sealing is poor, then you will find the next weakest link in the chain with a fresh head. BTDT.

175K is light. My 5VZ was pushing on 280k. I cant imagine your bottom end is toast yet. I may spend the 3K for a fresh head if I were you. Not unusual to have to clean up aluminum heads at 200k.

I would DO IT if the vehicle is good to go otherwise. 175K is nothing.

A misfire is often the first sign of burnt valve on the 3rz. I did my valves around that milage and they were very tight (like .0003 when min was .001), and they were done at least once before.

Get the compression tested by another shop to confirm you have low compression. If a little bit of oil doesn't help the compression, and you don't have any coolant loss, it's most likely valves.

People saying "it's a 4 cylinder, it should be easy" don't have any idea of removal cascade having 4wd causes. In short if you have a 4wd, the fallout of needing to remove the timing cover leads to removing the front differential or lifting the engine up. If it's 2wd, it'll be much easier.

I'm often amazed when people complain about timing belts... But if you have to remove the oil pan to repair the timing system, things are getting pretty complicated... (not hating on the RZ engines, just a general comment)

-Charlie

I think it's that bad because they used a chain. In theory the chain is good for the lifetime (or at least it is not the weakest link), and it's been proven true since I've never heard of someone taking it apart just for the chain.

Both engines require removing the front diff to do the oil pan gasket. But I think the only the 3rz needs the oil pan to be removed.