I just had my 1998 in to the mechanic for a random misfire code. No codes showed on the live counter, until the engine was allowed to cool (I have also had an on going cold start issue), and spraying parts cleaner at the intake body caused a noticeable increase in noise. He said the intake manifold gasket was bad and would need to be replaced, he said the leak was still minor and seemed to go away once the engine gets to 150 degrees or so but would get worse. Be said right now there is no fluid leaking it’s just a vacuum leak. He quoted about $600 to fix it.

Do you think he was right?
If the intake manifold casket is bad is $600 a reasonable cost to replace it?
Is this something that can wait until next summer? I have other pressing repairs that need done too like rebuilding the suspension (or at least replacing my CV joints and wheel bearings to get my ABS back), I could use a new power steering pump (it has a slow leak) and winter is coming up.
Will the cold in the winter make it undrivable, or unstartable?
Since replacing the intake manifold gasket involves taking apart the whole top of the engine, would it be worthwhile to preemptively go further and replace the head gasket? The head gasket has given me no indications of trouble, but if it could be done without much more cost it might be worthwhile just to replace it for the peace of mind. About how much more do you think that would cost?

This truck is normally just driven around town until I complete repairs, but if this is not done yet, do you think the truck would be OK to drive like this over the holidays (about 2 hours by freeway each way)?

 

When I first learned about how the lower intake manifold (LIM) gaskets (the ones next to the heads) could fail catastrophically with little or no warning and dump coolant into the lifter valley and ruin the main bearings, I immediately made plans to replace them.

As for the quote, $600 is about 5 hours of labor plus parts. That is not unreasonable to me as I took a whole day to do it. LOL If it had been my 68 Mustang with a 289, replacing the intake manifold gaskets would be a snap. But with our 4.3 Blazers, there is a LOT of stuff to move out of the way before you get to the LIM gaskets. I found it really annoying to do because the engine compartment is so cramped and there are brackets to move out of the way.

The issue is that the original LIM gaskets had a plastic carrier frame that would slowly dissolve. There replacement ones by FelPro that have a metal carrier that everyone uses.

When I did mine, I also took the opportunity to replace the fuel injection spider with an upgraded one. This was probably excessive on my part but the truck was 18 years old at the time.

As for the best write up on replacing the gaskets, I'm attaching pdfs of a webpage that described it well. The link seems to be broken but here it is anyway: http://www.handymanlyness.com/archiv..._99_Jimmy.html

 

$600 is a reasonable rate for a mechanic to do this job. Just be sure the replacement is the Fel-Pro with the metal core.

 

Would it be worth it to Preemptively do the head gasket too, or would that just add significantly to the cost?

Assuming it’s the Fel-Pro, how long can I expect the replacement to last?

Which should I put priority on, this or the wheel bearings and CV joints (to get my ABS working again)? I’ll only be able to do one or the other before winter.

 

If installed right new felpros should last engine life time.

Price will prob be over double by doing head gaskets - { at 600 I need to raise my rates }

I replaced mine as I wanted to check out and new valve stem seals on my heads - so its up to you but if you haven't over heated it they should be fine as they usually don't have problems.

And for priority its a toss up - wheel bearing go out it sits until replaced, lowed bearing are aluminum now instead of old school brass/babbet so intake leaks antifreeze into crank case the lower end on engine get trashed in minutes .

 

I have not heard of the original head gaskets going bad. Do you have reason to think they are bad? Is there some other reason to have the head removed? You could try a compression test to see if there are issues with the valves. But even valve jobs are things I have not heard of people thinking they need them.

I would expect the upgraded FelPro LIM gaskets to last 200,000 miles at least as long as the engine gets is regular service.

As for what to have fixed, that is tough. As I said, as soon as I heard about the LIM gaskets failures and having decided to keep the truck for at least 5 more years at the time, I decided that my next big repair would be to replace them. However, I did not have any indication of any leaks at the time. Although when I took the old ones out I saw where they were starting to fail.

Because you already have symptoms of the LIM gaskets going bad, I'd be tempted to move them to the top of the list of things to get done. If you are only driving around town, replacing the suspension components could be delayed but I would not want to take it on long trips. This also depends on how bad those suspension component are.

Can you tell us more about how the bad CV joints and wheel bearings (I'm assuming the front bearings) are and how their poor condition is related to the ABS not working? Are the front wheel hubs so worn that the ABS sensor toothed ring is no longer in alignment with the electromagnetic sensor? If so, that would be a major problem and I'd be tempted to only drive a vehicle in such a condition to the shop where it would be repaired.

Now, it sounds like some of the calculus here is that you are going to have to pay someone to do any of the work. Am I right? But if doing some of the work yourself is an option, the front suspension work is definitely within the realm of possibilities of even home mechanics who have only done brake pads. It is a little more involved but to replace the CV joints/axles and front wheel hubs is just more involved. Any special tools needed can be borrowed or rented from just about any auto-parts stores (Autozone and O'Reilly's are the ones I use.) To replace the LIM gaskets is a bit more involved and there are a few things that need to be done properly. Someone with more experience would be more comfortable doing that. In contrast the front end components are more of a bolt on type of situation.

 

ABS light is on and there is a clicking noise when moving slow, especially when stopping or starting. The front break pads and rotors have been replaced, less than 1,000 miles ago. Mechanic says the noise is coming from the front wheel bearings (on both sides) and speculates that is also likely what is causing the ABS light to be on. The CV joints are unrelated, they are just starting to go bad and it was recommended to replace them at the same time as the wheel bearings to save on labor. An important note is that the sway bar links and shocks are also bad.

I would be tempted to try the wheel bearings myself if I had someone more experienced looking over my shoulder, but the CV joints kind of weird me out, just seems like something where a mistake would be expensive. I am not mechanically inclined and have extremely limited tools, I’m trying to learn, but my confidence and knowledge about this stuff are still very low, so most things still get sent to the mechanic.

 

Ah yes. It sounds like those bearings are shot. If you jack up the front of the truck, you can check if the bearing are bad yourself by grabbing the wheel at the 3 o'clock and 9 o'clock positions and rocking back and forth. If the wheel moves but no other parts of the suspension moves, then they are bad. This should be repeated but by grabbing the wheel at the 6 and 12 o'clock positions. Of course, you should follow all safety procedures when jacking up a vehicle.

For the CV joints, they are hardly if ever rebuilt and instead the whole axle is replaced because of the relative costs of a new part vs. the labor costs in rebuilding the joint itself. I did replace the boot on one of mine but I knew I could because the boot had only very recently slipped off and there was no looseness in the axle. If yours are shot, I'm guessing your mechanic would be going with replacing the whole axles.

Because your mechanic is so familiar with your vehicle, does he have some thoughts on what repairs to prioritize? No matter what, you should start budgeting for the front end and the LIM gaskets to be replaced.

Perhaps someone else can put in their 2-cents on this too.

 

BTW, I stumbled on this description of what happens with the LIM gaskets and the years affected.

https://troubleshootmyvehicle.com/gm...nifold-gaskets

 

Does this normally also include a coolant flush and fill and servicing the coolant system?

I have no maintenance records and the manual says it was due for a coolant system service awhile back, I’ve been going through the maintenance list doing everything, on the assumption that it may never have been done since I don’t have the records and it would be nice to cross that one off of my list.