Engine knocking after overheat (1 Viewer)

[K Dub]

Thread title says it all, but here are the details re-posted from a clubhouse thread. The incident happened on a long, steep incline on I-5 north of Los Angeles called "The Grapevine". It's a notorious car killer. The A/C was off and it was 65-70F outside. I was driving around 55-65 mph in 3rd with O/D off, so 3-3.5K rpm or so for a prolonged time under load.

Just past the Pyramid Lake exit the temp gauge shot up. I got over to the shoulder just as it approached the red, never into red but just below it. I idled for about 5 minutes, a small amount of coolant escaped the overflow tank (a cup or two is all), and the temp dropped right back down. I knew it was only another mile or two to the Smokey Bear Rd exit, and the freeway shoulder was too narrow for comfort, so I made a run for it. The truck was way down on power and has a horrible knock at 1800rpm and up. I got off at smokey bear and parked by the fruit vendor at the Hungry Valley south entrance just as the temp was climbing back up. I idled it till the temp dropped again and shut her down.

Engine idles fine, still have plenty coolant, oil doesn't seem over full or milky on the dip stick.

The truck will be fixed. I just haven't figured out what all it needs and how I'm going to fix it. I've got to diagnose the overheating first. I know the bottom end will need work, and of course a head gasket, but I wouldn't do that without figuring out what caused the temp to spike first so it won't happen again. I'm a 1-2 banana mechanic at best; mostly fluid changes and brakes. I've done a few alternators, a power steering pump and some suspension work in the past but nothing on the 80.

The truck came with a plastic radiator installed when I got it last August. PO said he'd done the thermostat and radiator as PM a year ago along with dizzy o-ring, plugs and wires and intake hose. Seemed like normal '80 stuff to me so it didn't set off any alarms at the time of purchase. The truck has been driven much harder, in hotter temps, in the past without any temp variation on the factory gauge. (I know the factory gauge wasn't telling me much, point being I had no prior indications of a problem).

First thing on my to do list, after clearing out some space in the garage, is to drain the fluids pull the plugs and look around. Should I bother with Blackstone labs knowing that my engine needs work? I'd like to do a leakdown test on it, should I do that before I drain the fluids? Is that a tool I can rent?

I'm thinking of trying to remove and re-install the engine myself. This is far beyond the scope of my abilities, but there's only one way to learn and I have the best resources in the world on this forum. Could I deliver a complete long block to a machine shop and receive back the same, or do I need to disassemble/reassemble?

Should I cut my losses and go lease a Prius? Naaaaaaaaah. But I'm gonna need a lot of help.

 

[NorCalFJ100]

I'd personally do a full diagnostic check. Compression test, leak down test and inspect all fluids. I'd plan to baseline entire coolant system... radiator, hoses, thermostat and flush. All OEM.

As far as knocking I am not sure what would've cause you to spin a bearing while your temps were climbing. But you may get away with dropping the pan and replace the bad bearings without a full rebuild and or pulling the motor...if trying to go the minimal route.

Most machine shops will need you to drop off your block either short block or long block. They'll return it the same way. Due to the lack of 1FZs out there you probably won't find a machine shop that has one already built. You'll have some down time while you wait for yours to be done.

Pulling the motor seems daunting, but it's really very straightforward in these rigs. Can be done in a weekend pretty easily if you have all the proper tools and space to work in.

 

[Desert Dino]

The OEM temp dose not move, and when it approached the red its too late.

 

[ccslider]

You can buy a used motor from @Deathvalleypaul I'm sure he has a few good ones on hand.

You then have a few choices like if should you do the head gasket before installing it in the truck.

Or just stick it in and run it.

 

[Marco Lau]

I had that happened to me prior to my radiator upgrade, my temp would creep past half mark and approaching 3/4 into red towards the top of the climb. if no lost in coolant due to crack radiator or hoses, my bet is the coolant level is low and or you have air in the system. Also turning on your heat will help dissipate heat as well. If still overheats most likely you will need to upgrade your radiator. Also did you upgrade your fan clutch with thicker oil?? Also sealing the gap between radiator and fan shroud helps to pull air more efficiently as well. If your motor turns out OK, i would start from there. Good luck, i had gone thru what you had experienced in the past and it is NO fun. Keep us posted, you know how to reach me. best of luck.

 

[Marco Lau]

BTW..get a real temp gauge when this is all said and done. The stock gauge fluctuates between 165- 215F and the needle doesn't budge. You are a few degree from knocking on danger zone, and in reality you think your engine temp is fine. My all alum. radiator spikes to 195 F or so at the top of the grapevine fully loaded with 4 people and full armors in summer heat- stock gauge sits dead middle, while before i upgrade my radiator, my aftermarket gauge hits 215 plus at the top of the same climb and stock gauge sits dead in the center......

 

[NorCalFJ100]

This may be helpful 93-97 Coolant Temperature Gauge Modification

 

[K Dub]

I've given myself until mid June to get this turned around. I work slow, and I figured that the machine-shop time might be an issue. I like the idea of rebuilding my engine, but I'm considering a second engine as a "quicker" fix. I looked at a couple of "reman" engines online for $3-5K, or parts cars for about the same price, but who knows what I'd end up with. I think I'll reach out to DeathValleyPaul to explore my options further. Having a second block afterward could be fun too; maybe I'll make a coffee table.

I like the sound of dropping the pans and replacing bearings on the car, but something tells me the head gasket didn't survive either. Either way, I know my next step is simply diagnosis. I keep getting way ahead of myself.

I read that whole RavenTai thread a month ago, but I think I'd rather have actual temps to reference like Marco's suggested. I'm going to upgrade the fan clutch and switch to an OEM radiator. I'm considering deleting the rear heater too along with any other cooling mods I can find on here. I won't be caught with my pants down and my needle rising again after this.

 

[K Dub]

I'm leaning toward getting a replacement engine. Here's what I'm thinking:

Hopefully I find a running used 1FZ-FE with less than 200k on it. Replace the head gaskets along with all accouterments and sundries with fresh OEM parts. Strip the cooling system from my truck and order up all new OEM replacements from radiator and thermostat to PHH. Put refreshed engine and new cooling parts next to my broken truck and start calling in favors.

I've got a friend who's offered me a hoist, thanks @fjl40. I think I know who to call for the parts @beno, @NLXTACY. I haven't heard from @Deathvalleypaul, but I haven't been ready to buy anyways because I still have questions for the forum hive mind:

Do I need a pre '95 engine or will any year swap (I've searched, it gets less clear the more I look)?

Should I plan on valve stem seals too?

If so, should I outsource the head work and attempt reassembly myself or just throw the whole long block at a machine shop?

Am I getting in way over my head like all my friends seem to think? Any work within the block or head is out of my area of abilities. But I've read a lot on here about HGs and engine removal/replacement and I feel like I could pull that off given enough time and access to the right tools. That kind of delusion of ability has gotten me in trouble before. I'm a walking embodiment of Dunning-Kruger.

Thanks again for everyone's help.

 

[slow95z]

What year engine do you need?

 

[maxamillion2345]

I think you’re better off keeping the engine you have. I’d investigate what the probelm is first anyway.

Pull some spark plugs, borescope the holes and see if you still have crosshatch - look for scoring. Id expect the headgasket to go before sticking pistons but who knows.

If you dont find anything there, drain the oil and look for glitter, then drop then pan and start pulling main and rod caps one by one and inspect bearings.

Do you need a rebuild? Find the source of the noise first.


If you do go through with rebuild. Pull the engine and take it to a reputable rebuilder. I’d have the block hot tanked. Honed. Inspect crank, see if it needs polished. Inspect deck for warping. Have had inspected for cracks and warping. Might need milled. New valve guide seals at the minimum. I’d inspect valve seating surfaces too.

 

[Pin_Head]

This is very strange, but if it only “knocks” above 1800 RPM, it is not likely to be a bad crank bearing. Does it knock above 1800 sitting still in your driveway?

The PS pump / oil pump idler gear can make a knock that sounds a lot like a crank bearing.

 

[K Dub]

What year engine do you need?

I'm not sure, but mine is a '93. How close to my build date do I have to shop? Would a '94 work?

I think you’re better off keeping the engine you have. I’d investigate what the probelm is first anyway.

Pull some spark plugs, borescope the holes and see if you still have crosshatch - look for scoring. Id expect the headgasket to go before sticking pistons but who knows.

If you dont find anything there, drain the oil and look for glitter, then drop then pan and start pulling main and rod caps one by one and inspect bearings.

Do you need a rebuild? Find the source of the noise first.


If you do go through with rebuild. Pull the engine and take it to a reputable rebuilder. I’d have the block hot tanked. Honed. Inspect crank, see if it needs polished. Inspect deck for warping. Have had inspected for cracks and warping. Might need milled. New valve guide seals at the minimum. I’d inspect valve seating surfaces too.

This post is why I'm leaning toward replacement. The only part of that I feel confident I can do myself is "pull plugs" and "drain the oil and look for glitter". I watch a lot of YouTube, but I've never been inside an engine myself. I've never even seen a crankshaft in person. Isn't all that labor for diagnosis only adding work? The machine work would certainly cost more than a replacement engine. Not to mention the downtime with the engine out. So what's the upshot to fixing my damaged engine? I've only had it since August, so I don't have a known history of this any more than I would a used motor.

With a used motor I could have the head worked on while I'm at home readying the truck. I would have the replacement motor built and ready when it's time to pull my old one out. I could get away with only needing the hoist once. If I undid all the accessories down to the motor mounts and bell-housing bolts before calling in help, I might pull off the swap in 1 day. Then I could manage bolting everything back up myself.

 

[K Dub]

This is very strange, but if it only “knocks” above 1800 RPM, it is not likely to be a bad crank bearing. Does it knock above 1800 sitting still in your driveway?

The PS pump / oil pump idler gear can make a knock that sounds a lot like a crank bearing.

Yes, it happens while parked or under load, always above 1800. Sounds a lot like the startup rattle, but maybe louder and deeper in the engine compartment. I can try to get a video, but the tow truck driver just cringed when he heard it. Also, it's way down on power and overheats under any load at all.

 

[slow95z]

93 and 94 are the same and I have some used engines but shipping would be expensive across the country. Check with @Deathvalleypaul

 

[Pin_Head]

More likely a timing chain / oil pump drive issue than a crank bearing. Bad crank bearings make noise at all RPMs. None of this would be causally related to a slight over heating.

 

[K Dub]

More likely a timing chain / oil pump drive issue than a crank bearing. Bad crank bearings make noise at all RPMs. None of this would be causally related to a slight over heating.

Thanks for working with me. I've read about knock under load and other cases where the knock wouldn't happen at idle. Is that rare? I would love it if my crank didn't need to come out. Anything but that, in fact, I think I'd be okay with.

As for causality, how about the other way around? Could increased friction from a bearing failure cause the overheating? Could the knocking be coming from the water pump, hence the overheat? That would be nice.

 

[ajax1]

You can use a engine from 93 to 97, for the 95 and up to work you’ll keep your intakes and exhaust, you can swap your oil pans or not be a couple extra sensors on 95 up. It is way harder going 93 94 to 95 and up

 

[maxamillion2345]

I'm not sure, but mine is a '93. How close to my build date do I have to shop? Would a '94 work?



This post is why I'm leaning toward replacement. The only part of that I feel confident I can do myself is "pull plugs" and "drain the oil and look for glitter". I watch a lot of YouTube, but I've never been inside an engine myself. I've never even seen a crankshaft in person. Isn't all that labor for diagnosis only adding work? The machine work would certainly cost more than a replacement engine. Not to mention the downtime with the engine out. So what's the upshot to fixing my damaged engine? I've only had it since August, so I don't have a known history of this any more than I would a used motor.

With a used motor I could have the head worked on while I'm at home readying the truck. I would have the replacement motor built and ready when it's time to pull my old one out. I could get away with only needing the hoist once. If I undid all the accessories down to the motor mounts and bell-housing bolts before calling in help, I might pull off the swap in 1 day. Then I could manage bolting everything back up myself.

I mean maybe its added work, maybe it’ll save you work time and money. Either way I’d find the issue before going whole hog and yarding out the engine. None of diag stuff is very hard. Even pulling bearing caps and bearings.

If you intend to have the replacement engine fully gone through like you would the existing then... theres no downside other than added cost of sourcing a 2nd engine. If you’re gonna just source a random ‘lower mile’ engine and just swap well then IMO you’re taking a gamble. Either way, if you have to tear into yours - i’d have it checked out. If you source another engine, I’d have it checked out.

Best bet, do some diag work yourself before going any farther.

 

[K Dub]

You can use a engine from 93 to 97, for the 95 and up to work you’ll keep your intakes and exhaust, you can swap your oil pans or not be a couple extra sensors on 95 up. It is way harder going 93 94 to 95 and up

Thanks, that's about what I thought. My '93 has PAIR etc, but that can all stay on the truck. I knew about the extra sensors, but like you said it's harder to go back in time than to have sensors I don't need. My only problem is that Cometic head gaskets say they're only for '95 and up and that's making me question if the differences are more substantial.

I mean maybe its added work, maybe it’ll save you work time and money. Either way I’d find the issue before going whole hog and yarding out the engine. None of diag stuff is very hard. Even pulling bearing caps and bearings.

If you intend to have the replacement engine fully gone through like you would the existing then... theres no downside other than added cost of sourcing a 2nd engine. If you’re gonna just source a random ‘lower mile’ engine and just swap well then IMO you’re taking a gamble. Either way, if you have to tear into yours - i’d have it checked out. If you source another engine, I’d have it checked out.

Best bet, do some diag work yourself before going any farther.

I figured the 2nd engine would get all the same PM type work that my current one needs, minus whatever bottom end work mine might need. The added cost of the used engine would be offset by not tearing into the bottom end and the time saved which would be substantial. Doesn't the engine have to be out before I start pulling bearing caps and bearings? At that point I just want to drop a new one in.

I haven't progressed on my diagnostic all week, because I was dealing with my new daily driver (a borrowed 2001 Honda Accord with a dead battery and starter). It took me until Thursday to get that car reliable enough to trust, but I don't mind fixing it up a bit if I'm driving it around for free. It had been sitting almost 6 months when I picked it up. I can't look that gift horse in the mouth, but driving it does motivate me to fix the truck.

I'm going to run it this afternoon to move it into the garage. I'll take a video of the sound. Once in the shop, I'll pull the plugs and start taking a closer look. I'll let y'all know what I find. Thanks again for all the help and patience.