Blown gasket in 2000 gmc advice?

Hello, I recently blew a head gasket in my 2000 gmc Sonoma according to my mechanic. He told it would be 1.2k for a new gasket or 4K for a new engine, as he didn’t recommend changing just the gasket alone due to the age of the truck.

Before the blown gasket, my truck was in excellent shape to be so old. I never noticed it running hot, so whatever caused it to happen must’ve come on suddenly. I only paid 1k for it two years ago, but I don’t want to let it go.

Would it be worth changing the gasket alone at all? What sort of questions should I be asking? I know nothing about cars at all and I feel so lost. Please help?

This is a 4 cylinder engine? Did your mechanic find the cause? 1200 seems somewhat high if it is a 4cyl. Truck may not be worth putting that money into, especially if there are other issues on the horizon.

This is a 4 cylinder engine? Did your mechanic find the cause? 1200 seems somewhat high if it is a 4cyl. Truck may not be worth putting that money into, especially if there are other issues on the horizon.

He didn’t really say anything except that it’s blown and he wouldn’t recommend changing the gasket alone due to how old it is, and insisted I change engine if I want to do anything. I wasn’t sure what questions to ask. The car won’t crank at all - could it be something other than a gasket causing it not to crank? I don’t trust mechanics completely because I am car illiterate and I think they can tell, and I’m kinda wanting a second opinion but I would have to tow it to another place and pay for another diagnostic.

So when you say the engine won't crank at all, do you mean the starter motor will not spin the engine over? Some people say "crank" and actually mean "start" and others mean the engine doesn't spin, so I'm hoping you can clarify.


If the starter motor engages and tries to spin the engine over but doesn't have enough power to, that could be a severely hydrolocked engine which could be due to a head gasket, but in that case the tech should pull the spark plugs to release the load from the engine and try again. The starter should then spin the engine over without struggling and spray liquid all over from the open spark plug holes.


Just based on the information provided so far, you may want to get a second opinion after towing the truck to another shop that a friend or co-worker trusts.



-Rod

So when you say the engine won't crank at all, do you mean the starter motor will not spin the engine over? Some people say "crank" and actually mean "start" and others mean the engine doesn't spin, so I'm hoping you can clarify.


If the starter motor engages and tries to spin the engine over but doesn't have enough power to, that could be a severely hydrolocked engine which could be due to a head gasket, but in that case the tech should pull the spark plugs to release the load from the engine and try again. The starter should then spin the engine over without struggling and spray liquid all over from the open spark plug holes.


Just based on the information provided so far, you may want to get a second opinion after towing the truck to another shop that a friend or co-worker trusts.



-Rod

Thank you for your reply! When I crank the car with the hood up I see something in the middle spinning. It makes the juh juh juh noise like it does usually when cranking but never completes. I’m not sure if that’s what you mean but I hope that helps.

Based on that description, it sounds like the starter motor is spinning the engine over, it's just not starting. A blown head gasket certainly wouldn't be the first conclusion I'd jump to in this case. You need to find out if the shop has confirmed good spark, good fuel injector pulse, good fuel pressure, checked compression on the cylinders, and performed a cylinder leak down test or combustion gas test on the cooling system to determine that you have a bad head gasket.

I suspect they don't really know what's wrong and they're giving you a worst-case scenario, but if that's the case, or if they haven't performed the tests mentioned above before deciding you need a new engine, you really should find another shop to at least get a second opinion.

-Rod

Amen on the Shorod' s advice

You have been so incredibly helpful, thank you for your advice! I just gave them a call and I asked if I could speak to the mechanic who worked on my truck, the one who answered said he’s the owner I don’t need to speak with them. He said he can tell me what is wrong and that a combustion test and coolant tester was done and coolant is shooting out, “it’s an obvious blown gasket”. Then he hung up on me before I was finished talking which isn’t really relevant info but I thought it was super rude haha.

What do you think about the combustion test/coolant shooting out etc?

So when you say the engine won't crank at all, do you mean the starter motor will not spin the engine over? Some people say "crank" and actually mean "start" and others mean the engine doesn't spin, so I'm hoping you can clarify.


If the starter motor engages and tries to spin the engine over but doesn't have enough power to, that could be a severely hydrolocked engine which could be due to a head gasket, but in that case the tech should pull the spark plugs to release the load from the engine and try again. The starter should then spin the engine over without struggling and spray liquid all over from the open spark plug holes.


Just based on the information provided so far, you may want to get a second opinion after towing the truck to another shop that a friend or co-worker trusts.



-Rod

As far as what they did, it's not yet clear if they mean they measured combustion gases in the coolant and, when running, the coolant was bubbling in the radiator. That wouldn't quite make sense since you said the engine won't start. The other possibility is they pressurized the cooling system with a pump and noticed coolant seeping out between the head and the block which would be indicative of a bad head gasket, but in this case it shouldn't prevent the engine from starting and, unless the gasket is leaking in more than one location, wouldn't explain combustion gases in the cooling system.

Based on their lack of detail and seemingly rude attitude, I personally would not be inclined to give them any of my hard-earned money, but that's a choice you'll need to make for yourself. Unfortunately I suspect you're going to have a bit of a fight on your hands if you tell them you want to take the truck elsewhere. If you opt to pick your truck up and take it elsewhere, from the little amount of testing they've admitted to doing, I wouldn't expect the bill for their time and materials so far to come to more than $100-$200.

I wish you the best of luck in getting this resolved!

-Rod

He mentioned something about putting a dye in the coolant as well. I know they are already planning to charge me $100 for a diagnostic. I am not happy about paying it but I will, unless I do decide to get a second opinion and it turns out they were wrong. As far as I’m aware the truck still won’t start. I appreciate all of your input!!!

As far as what they did, it's not yet clear if they mean they measured combustion gases in the coolant and, when running, the coolant was bubbling in the radiator. That wouldn't quite make sense since you said the engine won't start. The other possibility is they pressurized the cooling system with a pump and noticed coolant seeping out between the head and the block which would be indicative of a bad head gasket, but in this case it shouldn't prevent the engine from starting and, unless the gasket is leaking in more than one location, wouldn't explain combustion gases in the cooling system.

Based on their lack of detail and seemingly rude attitude, I personally would not be inclined to give them any of my hard-earned money, but that's a choice you'll need to make for yourself. Unfortunately I suspect you're going to have a bit of a fight on your hands if you tell them you want to take the truck elsewhere. If you opt to pick your truck up and take it elsewhere, from the little amount of testing they've admitted to doing, I wouldn't expect the bill for their time and materials so far to come to more than $100-$200.

I wish you the best of luck in getting this resolved!

-Rod