Severe Engine/Compression Issue - Next Steps? (1 Viewer)

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Joined
Jul 13, 2017
Threads
1
Messages
24
Location
Richmond, VA
Hi All! I've been a reader on this forum since June 2016 when I picked up my 1994 FZJ80, but this is my first post. Apologies in advance for the lengthiness, but I'm sure the more information I provide, the better you can advise me on moving forward. I got my LC from a local guy who said it had some issues when he got it, and was told his "mechanic friend" put a head gasket on it, and he was only selling it because he needed a pickup truck for his landscaping business. It has 260k miles, zero rust, tinted glass, a clean carfax, and good tires. The hood and RR quarter have really bad clear coat peel. For $2800 and "with a brand new head gasket", it seemed like a pretty good deal. It was running fine when I got it other than some minor vacuum leaks and throwing a knock sensor error(come to find out, there wasn't a knock sensor present which I corrected). I changed the oil and transmission fluid when I got it, as well as the v belts and I'm sure a few other little items that seemed worn out. I also installed an upgraded sound system as I enjoy music and used to be a Geek Squad Autotech(I have my MECP Advanced Certification and am much more experienced with the 12 volt side of things than the mechanical side). Beyond that, I haven't had any issues and have simply driven her a few times a week when the weather didn't suit driving my corvette. The check engine light has come on a few times with the EGR code (71? I can't remember) but i had read here that this was a somewhat common issue that most people ignored.

A month ago, I was pulling off from a stop light and I noticed a sudden change in power and a roughness that hadn't been there before. It was very obvious that something was up, but nothing horrific or seemingly serious. I pulled over, looked over my vacuum lines, etc, and didn't see anything abnormal so i kept an eye on my gauges and limped a couple miles home. It didn't have any codes except for "running rich" which lined up with a miss somewhere so I figured that I would do all the "normal" tuneup stuff first since I wasn't sure of the maintenance history: spark plugs(1-4 were a nice tan color, 5 and 6 were slightly fouled), wires, distributor cap, rotor, replaced any dry rotted vacuum lines/hoses, checked for cracks in the main intake hose, etc. None of these helped, and the rough idle and loss of power progressively got worse. I noticed that there was a hidden gap between my air filter housing output flange and the air flow meter(unfiltered air - what the heck), and after doing some research realized that the AFM that was on my truck wasn't the original one - it seemed like it was from a 3.0 perhaps? I'm guessing that the original died and someone pulled something from a junkyard that "fit", but obviously was an issue so i found a remanufactured one on eBay and replaced it. This was over the past few weeks as I found parts and time, and the rough idle and power loss got progressively worse until she started stalling unless i fluttered the gas pedal and now she will barely move around the driveway. I got a compression gauge and checked compression tonight. The dry readings were:

1-167
2-177
3-182
4-179
5-0(oh, crap)
6-0(oh, crap)

I've heard that 5 and 6 are classic culprits for head gasket failure on the 1fz-fe. As far as I can tell from several checks, there is no coolant in the oil, and there is no oil in the coolant. She hasn't lost any noticeable amount of coolant or oil. The exhaust isn't smokey, although it does seem a bit moist/sooty(i have gotten a small blue-black puff on startup since I got her). At this point, I'm aware that something internal is majorly screwed up, but my question is what seems most likely? And is it worth investing a potentially large amount of money into the truck at this point based on your experience? Im wondering if the previous guy lied to me and snake oiled the head gasket which just re-blew out, or if theres an issue with the head that caused a legitimate head gasket replacement to fail ~10k miles later. The other thing that seems possible based on what I've read is the valves, but I'm lost on how to test from here to figure out what exactly my actual problem is. I'm VERY good at learning and tackling any kind of repairs and rarely have other people work on my cars, and I have a garage and significant amount of tools, but I don't have experience with something as involved as an engine rebuild. Any pointers in the right direction would be hugely appreciated. I can provide whatever additional details might be helpful!
 
...
I've heard that 5 and 6 are classic culprits for head gasket failure on the 1fz-fe. ...

Most often 6 but yes. It is possible for the gasket to fail between cylinders, haven't seen this on 1FZ, but yes. I would remove the plugs in 5 & 6, move one to TDC for that cylinder, induce compressed air and see if it comes out the other suspect.

If you have a hose type compression tester it's pretty easy. Disconnect the gauge, wont be needing it. Look in the spark plug end of the hose, there should be a valve like in a tire, remove it. Screw the hose into the spark plug hole and connect an airline to it.
 
Most often 6 but yes. It is possible for the gasket to fail between cylinders, haven't seen this on 1FZ, but yes. I would remove the plugs in 5 & 6, move one to TDC for that cylinder, induce compressed air and see if it comes out the other suspect.

Great idea! I'll do that this weekend. Is there any way to find out whether it's a valve or other known issue? I'd be really happy to have a few different tests to go through in one sitting. Thanks in advance!
 
Classic 5 - 6 failure IMO. This could be caused by many things, a simple bit of crap on the gasket, pinched fire ring, head not cleaned, if you can beg, steal or borrow a bore scope you will the tops of the pistons are different in colour and texture to the other four, perhaps even see the failed fire ring between the cylinders?

Regards

Dave
 
Post a picture of the six spark plugs inline with each other, #1 thru #6.
 
Great idea! I'll do that this weekend. Is there any way to find out whether it's a valve or other known issue? I'd be really happy to have a few different tests to go through in one sitting. Thanks in advance!

With the target cylinder at TDC and the other plug out, apply air pressure. A correctly working cylinder should hold the pressure (mostly). One that has no compression will signifacantly leak, where does it come out? It should never come out the adjoining cylinder, if it does, the gasket is gone between them. Check to see if it also comes out the exhaust, intake, etc. But with the rest having good compression, it's a pretty good bet that the gasket is gone between those two, this just fully confirms the deal.
 
You can put a little oil in the cylinder and do the compression check again. If the compression jumps up its probably a cylinder or ring issue. If it stays the same it could be a valve issue.
 
Alright, I found some time this afternoon to do some more diagnostics:

@Tools R Us , thanks for the air pressure test idea, I did this and when applying air to 6, it came out of 5.

@BILT4ME , I don't have the original plugs, and the current set are all heavily fouled because of how rough it was running - the set that was running during the original were:
1-4 - normal, slightly white/grey, completely dry
5-6 - looked fouled and damp, which I'm guessing is from unburned fuel. They looked how all my plugs look now.

@Dave 2000 , I can buy a bore scope if necessary; based on the other tests it seems I have no head gasket between cylinders 5&6. It's my thinking that even if additional problems are in there, I'm going to see it when I take the head off to do the gasket.

@450LX I also tried those two cylinders "wet" by adding about a tbsp of oil to the cylinder, there was still no compression.

So, all this said, what would you guys do next if she was your rig? I can and will attempt anything, as long as I have a clear understanding of the task or instructions. It sounds like the gamble is that if the PO really did the head gasket, there might be an issue with the head or block that would make an additional head gasket another waste of time. On the other hand, his backyard Russian friend might have just goofed it. Is there a reputable head and lower rebuilt kit that you guys would recommend? If I'm going to take the head off, I'd rather do it once and make everything as new as possible. Is it foolish to go that far, and not get new sleeves pressed in and the head tested and machined back to spec as necessary? I don't mind spending some money on it if it's a long term good investment, but I also don't want to pour money down the drain if I should go find something that doesn't have 260k miles. Thanks for all your help!
 
Pull the head, have the face checked, and then have it pressure tested. Check for block damage but TBH it should be fine.

I would go for OEM gasket set unless someone had a better alternative?

Regards

Dave
 
...
@Tools R Us , thanks for the air pressure test idea, I did this and when applying air to 6, it came out of 5.
...

No compression in adjoining cylinders points to gasket failure between them, air applied to 6 with the valves closed and coming out 5 says the same. Pull the head and inspect.:frown:
 
Yup X3........

My condolences.....
 
@Dave 2000 , @Tools R Us , and @BILT4ME Alright I guess it's decided then; so I am planning to pull the head off, take pictures, and make decisions from there - I searched on the forum without luck - do you guys know of a good step by step resource for that procedure? I called around to a couple machine shops and they quoted me $300-$500 for a head resurface and valve job - do you guys think that I need to have the head rebuilt, or is just getting it resurfaced sufficient? I want to get another 100k out of the truck if I'm going to put money into it. To that end, is there anything besides the head gasket and any related immediate issues that I should do while I'm already that far in? Thanks so much for all your help!
 
@Dave 2000 , @Tools R Us , and @BILT4ME Alright I guess it's decided then; so I am planning to pull the head off, take pictures, and make decisions from there - I searched on the forum without luck - do you guys know of a good step by step resource for that procedure? I called around to a couple machine shops and they quoted me $300-$500 for a head resurface and valve job - do you guys think that I need to have the head rebuilt, or is just getting it resurfaced sufficient? I want to get another 100k out of the truck if I'm going to put money into it. To that end, is there anything besides the head gasket and any related immediate issues that I should do while I'm already that far in? Thanks so much for all your help!

Do whatever @Tools R Us tells you to do.

Fortunately, my PO did mine and had it all done at a Toyota Dealer. They rebuilt the head, checked both head and block for warp, reassembled all with new hoses and water pump. My truck burns NO oil. Has a few drips yet here and there. 113K ago. (now at 258K)
 
@Dave 2000 , @Tools R Us , and @BILT4ME Alright I guess it's decided then; so I am planning to pull the head off, take pictures, and make decisions from there - I searched on the forum without luck - do you guys know of a good step by step resource for that procedure? I called around to a couple machine shops and they quoted me $300-$500 for a head resurface and valve job - do you guys think that I need to have the head rebuilt, or is just getting it resurfaced sufficient? I want to get another 100k out of the truck if I'm going to put money into it. To that end, is there anything besides the head gasket and any related immediate issues that I should do while I'm already that far in? Thanks so much for all your help!

Get the head off of it, take it to a reputable shop and have it inspected BEFORE you order any parts.

They will want check to see that the head isn't cracked, flame cut or warped beyond repair. The head can be 'resurfaced' but only slightly. IF too much is taken off the mating surface then the head will be pulled (warped) out of spec at the cam bores.

The vast majority of heads end up just needing a valve job and light resurfacing, BUT each one needs to checked out by a shop that knows what they are looking at and what they are doing.

IF your head turns out to be 'good', then you can move forward.
 
As above really, find a reputable machine shop, perhaps ask about on MUD, I cannot help with a recommendation as I live in Spain.

Dig out the FSM if you need a step by step guide but it will assume some mechanical knknowledge, if not sure then call on someone you know to at least guide and help uou. Re parts, check to see if new head bolts are needed, I would guess yes but call on the MUD skill base here, I have a personal preference for OEM gaskets, and you must think clean when assemnling.

Good luck,

Regards

Dave
 
Last edited:
@flintknapper and @Dave 2000 , I'm going to get the head off and go from there. I had a few hours this morning to start tearing down so I got her in the garage, hood and brush guard off, drained the coolant, power steering fluid and oil, and tore down the plugs, wires, intake, throttle cables and body, and got the wire harness out(wow, what a fun time that was - I see why someone sawzalled their intake lol).

Couple of questions:

is there anything I need to be especially wary of or careful for once I get inside the valve cover?

Are there any known proxy issues I should be dealing with while I'm in here? Everything is going to be super accessible.

Does the intake manifold need to be halved, or should I leave it together? Do I just unbolt it from the head or is there something special I need to do with the fuel injectors first? I'm trying to leave things in as big of connected pieces as I can to minimize reassembly confusion and time.

I looked and looked for the FSM, but I can't find one for the 1994 fzj80 1fz-fe. If someone knows of an active link that would be fantastic.

I'll keep updating and adding pics, hoping to get the head off in the next night or two.

IMG_5257.JPG
 
Got the manifold off - those bottom side bolts suck. Going to do some research on removing the distributor and camshafts, since those obviously need some specific handling to keep things timed correctly on reassembly. Is it a best practice to replace all metal gaskets on reassembly? So far I've come across ones for the throttle body>manifold, egr>manifold, and manifold>head.

IMG_5264.JPG


IMG_5265.JPG
 
Have you thought about sending your injectors out to be cleaned and serviced? Inspect your wire harness especially near the egr valve. Should probably put some extra insulation near that spot.
 
Pesky heater hose replacement while in there?

Regards

Dave

Yep, and the TB coolant hose and every other coolant hose and might as well replace all the vacuum hoses.
 

Users who are viewing this thread

Back
Top Bottom