When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
caleb, as @Chalt says, a "leak down test" is the next step. You can buy a leak down tester from Amazon for $32. It will be fine for what you need. Or you can probably get one as a free rental at the auto parts store. So shop air is going to be a problem if you are parked on the street. I might suggest you use the pressure in your spare tire to help do the test. You'll need to rig up an adapter hose that goes from Schrader valve at the tire to quick disconnect at the tester. It won't take much air to do the test. The leak tester has a pressure regulator that you throttle down to a low psi number. Like 10.
Alternatively, you can probably identify a valve that is not seating just by putting a proper size hose into the spark plug hole and blowing. Yes, you might get some strange looks but the price and hassle factor is very low. Test a known good cylinder also, just so you understand the differences.
Knowing what you are dealing with will be invaluable. BTW, I can't imagine a scenario where the rings are the problem, unless you just left them out entirely!
Got a leak-down tester. I had a little handheld air compressor, so it was kind of tough to dial in properly, but I think I got the hang of it. Tested cylinder 1, and the air was just pouring out of the exhaust. I wasn't getting any compression at all, of course. Didn't hear anything coming from coolant, oil, or intake. So I need to take the head off and see what kind of valve trouble I'm looking at. Also was getting some exhaust hiss from cylinder 2 (though not nearly as much), so expecting some fun surprises along the way!
Got a leak-down tester. I had a little handheld air compressor, so it was kind of tough to dial in properly, but I think I got the hang of it. Tested cylinder 1, and the air was just pouring out of the exhaust. I wasn't getting any compression at all, of course. Didn't hear anything coming from coolant, oil, or intake. So I need to take the head off and see what kind of valve trouble I'm looking at. Also was getting some exhaust hiss from cylinder 2 (though not nearly as much), so expecting some fun surprises along the way!
It's nice to know where exactly the trouble is before disassembly.
Now you have a new tool and a new skill that you can use on any car to diagnose compression loss.
Good news it isn't rings/bottom end.
Keep us updated.
Well... I was going to wait until this weekend to rip the head off this bucket of bolts, but I didn't really have any excuses to wait! Upon further inspection... I'm thinking there's something wrong here lol When I pulled off the intake manifold; there was some kind of fluid in the intake valve area of cylinder 1. Also, a small tear in the head gasket was letting some coolant into cylinders 2 and 3. Luckily, all of the cylinders and pistons seem to still be in great condition, so I don't think it caused much damage beyond these bent valves... On that note, it appears to be all 4 exhaust valves. The intake valves are all flush with the head, but the exhaust ones are black and slightly raised. This would explain why I could still hear air coming through the exhaust for all cylinders during the leak-down test. Overall, I think it's a good thing I did all this. I did some wonky hose/wiring routing when I initially put the engine back together. Good chance to clean that up significantly.
My one question for this is, are there any cheap replacement options? I see some intake valves going for $20 each, but exhaust valves seem to be in the $50/each range. It's also tough to find exhaust valves specifically for an '84 car. I know there was a significant change in (I believe) '88/'89, but will any of the exhaust valves up until then work? Just wanna make sure I buy the correct replacements, but money is tight at the moment, so anything I can do to save some pennies would be super cool.
The "cheap" option is to buy a known good used head.
If you want to rebuild it you will need new valves, cut/lap new seats, possibly guides (depends on if they were damaged during piston/valve contact). Based on this thread its probably best you send the head out to a professional machine shop to perform that work. Valve springs and lifters should be ok I would think. You may also possibly need pistons if they are marked badly by the valve contact
I'm a little confused. Are you saying when the camshaft lobe is "off" the particular exhaust valve in question, it is still visibly open? And as you rotate the cam shaft, none of the exhaust valves ever really close? If that is the case, then maybe they are all bent? Looking at the top of the head, if you place a ruler flat across the 8 valves, the tops of the valve stems should all be the same height. If the suspect exhaust valve stems are "low", then they are hung up due to being bent. Could have been caused by the timing belt slipping a tooth or too. Not tensioned correctly. See my PM.
What I am seeing in the above picture that the OP posted appears to be a bent valve that will not fully seat when closed, which is apparent in the angle that the valve currently sits. In the photo it does not appear the valve is set to a fully closed position but if it were, would not fully seat (or maybe it just cant fully close because the bent part of the stem is hung up on the guide). I would expect that there is a matching mark on the piston where the valve lip contacted.
I could be mistaken though.
One very simple way you can check valves to see if they are bent is to remove them, roll the stem on a flat surface (like the edge of a flat counter top) and see how much deflection the valve lip has while rolling. It should spin perfectly straight. Its not always apparent if a valve is very slightly bent just by looking at it.
Hopefully the damage was done by a previous owner (or bad luck with a snapped timing belt) and not the OP themselves through some gap in knowledge. Educating oneself and independently researching a particular workflow (especially timing because the stakes are so high) prior to touching a wrench is 90% of being a mechanic. An important lesson for anyone who works on their own cars.
Last edited by walfreyydo; 03-03-2023 at 12:15 PM.
Was hoping to have a good update for everyone, but somehow it just keeps raining in sunny Los Angeles! @harveyf was my knight in shining armor and sent me, not only the valves I needed, but also loaned me his Arnnworx tool to make sure I get my timing perfect. A true king! I replaced the bent valves/guides and got the head and cam tower back on, but then I noticed something... the fuel line has frayed (more like completely severed) right at the metal connector going into the fuel rail and started leaking fuel. I'm not sure if this is a new development from me moving it out of the way while taking the head off, if I somehow missed fuel dumping everywhere (I didn't), OR if it was maybe being held in place by the position of it until I moved it. This car is the gift that keeps on giving! By the end of all this, I'll probably have replaced 75% of the major parts on the car and I haven't even gotten to the cosmetic work I was excited to do when I got it hahaha At least I should be good to go for a while once it finally moves!
So anyway, now I ordered the fuel lines off Renbay and now I get to crawl around on the ground yet again! Seems like it's gonna be a special kind of inconvenient job! I know I probably need to go ahead and replace the fuel filter and strainer while I'm under there just to rule out any other fuel issues. Should probably go ahead and order those things too! Will report back when I get all that sorted out and I can time it properly in a few days when this neverending monsoon stops!
then I noticed something... the fuel line has frayed (more like completely severed) right at the metal connector going into the fuel rail and started leaking fuel. I'm not sure if this is a new development from me moving it out of the way while taking the head off
It is likely just age. Fuel lines eventually get dry rot, cracks, and leak, given the age of these cars. I seriously doubt you caused the fuel leak if the fuel lines were newer.
You are just very fortunate that you saw the leak while the car is not running again. You likely avoided an engine fire.
Great news that you are getting everything back together. And that's awesome that @harveyf helped you get valves. This is a great community.
I wouldn't wish the hell of replacing fuel lines on my absolute worst enemy. Literally took most of the day of crawling around on the ground, jamming my hands into the smallest possible crevice on the entire car. Then, I got the new connectors on there and realized that Rennline forgot to send me a small part to go between the connector and the hard line to stop fuel from leaking out (the main line appears to be solid, though I haven't tried starting the car yet, so preparing for the worse haha)... so hit them up trying to figure out what size I need so I can go grab one of those. I wanted to throw a wrench through a window when I saw the leak. Livid. THENNNNNNNNN the damn connector on the fuel rail appears to be absolutely rusted on as tight as it possibly can be. Was bending the metal line around trying to get it off, terrified of breaking something. Eventually got it off at a higher point and am soaking the S connector thing in a vat of WD-40 right now. Also realized that one of the little plastic vacuum connectors on the coolant line on the back of the engine snapped off, somehow. When it rains it pours! So close, yet so far... Managed to re-wire a new connector onto the harness for the speed sensor, so that's the one win I actually got today. Thought I was gonna get the car running, but still have a ways to go. Not sure why everything is deciding to fall apart right now at the finish line, but I think I've got it all sorted now. Gotta fix the fuel issue, then throw intake on and time it. Should only be a few more days now...
The one time I did it with the engine in, I remember the fuel line replacement to be a rough, tight go.
Regarding the broken off vacuum connector, perhaps you are talking about the thermo valve, item 28 on PET 103-00? If that is the case, it is not mission critical to starting the car. As I recall, it does not allow the fuel vapor charcoal cannister to purge to the intake unless the engine is above a certain temperature. If it is broken off, it does represent a small vacuum leak but again, I don't think it would keep the car from starting. You could temporarily plug the vacuum lines or you could use a connector (rubber hose) to join them. This connector has been broken off on several engines I have seen, as I recall.
WELL, WELL, WELL... Got the missing parts from Rennline and was able to finish the fuel line install. Put all the gunk back on the engine, timed it properly (huge, extreme, massive, major shout-out to @harveyf), and... THE CAR HAS STARTED! It's not running yet, but it is STARTING again. Instantly, too-- the fastest damn start I've ever heard a 944 do. Almost instantly it dies off, but whatever-- I'm running on pure euphoria right now. BUT, I think my new problem is that the old fuel line connector going to the S line on the fuel rail has all but been welded on. I got the S line off, but the power of 40 suns could not make this connector spin off. I've tried EVERYTHING and it will not budge. I've come closer to breaking the metal off with my bare hands than getting it to spin... Anyway, I suppose I must order a new one of those guys, which SUCKS. I attached the fuel line a little higher up, just for the purpose of testing, but it's leaking out, so I don't think I'm getting the fuel pressure I need to get the car running. Having some trouble finding this specific part though. Will this work? Doesn't exactly look like it would, but hard to tell. Are there any alternatives for this? Is there just a compression fitting that I can bypass the S with? I'm in the home stretch now!
Here’s a photo of the part. 944store.com has a replacement, but it only comes in a kit with fuel lines (that I wish I had seen earlier) and they said they won’t sell it to me on its own 😤... That connector on the top is the troublemaker here. Pretty much destroyed the part right below it with vice grips trying to get a grip on it enough to turn it (to no success). Gonna go grab some PB blaster or something (all I’ve had on hand is WD-40, which it soaked in a bath of for, like, 3 days straight) to see if that can break it loose, but I highly doubt it. Until I fix this, doesn’t seem like the car wants to start. Doesn’t seem like the fuel rail can build up enough pressure to keep the car running after the initial start… but hey, I’ve got great compression in all cylinders now and just hearing the car fire as well as it does puts a big ol’ goofy grin on my face.
03-02-2023 | 04:25 PM
