SHIFT Posted October 2, 2009 Report Share Posted October 2, 2009 (edited) I just purchased a 1973 Datsun pickup. A bit of background: It has an all new brake system including drums, pads, master cylinder and pump, recently rebuilt engine. The thing is ugly and a bit banged up, but I needed a reliable truck for A to B transportation. The guy I bought it from said the truck was running perfect. I took it for a drive and it ran like a top. I bought the truck. Well, I live about an hour away and about half way home (while going up hill) the car started to bog out and misfire. Any Ideas about the bogging and misfiring when going uphill? Also the brakes don't feel right- like I have to press pretty hard to stop- I don't have experience with drum brakes so I don't know if it's normal. I also noticed what I believe is brake fluid sprayed up into the engine compartment on the left side behind the battery. I checked the brake fluid and it's full and looks new. I checked the brake fittings and they seem nice and snug. My thought was that perhaps one of the fittings might be cross threaded and spraying brake fluid upward when the brakes are under pressure. These are 2 pretty important issues that I need to get squared away so that I can drive this thing safely. any input would be greatly appreciated. UPDATE: I found what I believe to be the source of the leak. I'm going to fix it. I still don't know what is causing it to bog out and misfire when going up hill on an incline. Edited October 3, 2009 by SHIFT update Quote Link to comment
moparvwfreak Posted October 3, 2009 Report Share Posted October 3, 2009 welcome aboard. i would check the points, if it has them still, and also the float level. it might be that the float is set too low so on a hill it would not get enough gas, hence the bogging and want to stall. Quote Link to comment
datzenmike Posted October 3, 2009 Report Share Posted October 3, 2009 (edited) Even more likely is an old fuel filter clogged with dirt. Fine for running around town, but on a hill more gas is needed by the carb than can get past the clogged filter and the carb runs dry. Just go ahead and change the filter, it's easy and they are cheap. If this doesn't help... no harm done. Edited October 3, 2009 by datzenmike Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 (edited) Hey thanks for the input. The fuel filter is new so I'll check the float level. If an adjustment doesn't do it then I'll go after the points and a new fuel filter just in case. I discovered that the oil leak was coming from the spacer behind the fuel pump. I'm going to order a new spacer with gaskets. Do you think the bogging down and missing could be related to this spacer issue? Edited October 3, 2009 by SHIFT Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 ok, I'm new at this... on the front of my carburetor is a glass window and behind it looks like it may be a float. Is that the float? How do you adjust it? I don't have a manual yet. Quote Link to comment
slam_dat_sun Posted October 3, 2009 Report Share Posted October 3, 2009 Hey man welcome to Ratsun and congratulations on your 620 purchase . We would love to see pictures of your truck ............... Quote Link to comment
moparvwfreak Posted October 3, 2009 Report Share Posted October 3, 2009 check out http://www.olddatsuns.com and download the 74 service manual. it'll give ya most of the info you need. most of the info in it is the same. thats what i did when i first got my 73. it'll work till ya get ahold of the proper 73 service manual. Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 (edited) Hey thanks for the tip on the service manuals. I'm downloading the 74 manual right now. I'll work on the truck tomorrow during daylight. I'll take some picks too. I didn't think I was buying a project truck... Edited October 3, 2009 by SHIFT Quote Link to comment
Guest DatsuNoob Posted October 3, 2009 Report Share Posted October 3, 2009 Pics! Or you're lying!:lol: Welcome, and feel free to fill out your location too. ;) Quote Link to comment
67_1600 Posted October 3, 2009 Report Share Posted October 3, 2009 I might check your timing and your vacuum advance. If your timing is a little retarded and/or your vacuum advance isn't working, the truck might run Ok but when under load you might see more of a difference. My timing was off recently on my Roadster and I had similar symptoms - it was fine around town but when I got on the freeway and put some load on the engine it would really bog down and I'd get some misfires. It also ran hotter than normal. Quote Link to comment
DatDoug Posted October 3, 2009 Report Share Posted October 3, 2009 Hey thanks for the tip on the service manuals. I'm downloading the 74 manual right now. I'll work on the truck tomorrow during daylight. I'll take some picks too. I didn't think I was buying a project truck... Ha-Ha! Dude they are all project trucks!:lol: Wether you pay $100 or $3000. You will figure out tho that they are very simple to work on. You just need the rite info, tools and patience.:D And of course "THE FORUM":cool: Ratsun.net RulZ:fu: Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 yeah, I bought it cause I figured it would be easy for me to work on, I just didn't think it was going to happen so soon :lol: I'm going to have to buy some tools. I just bought a manual on ebay. I have to take this one step at a time and get this bogging issue worked out. I never checked the timing on a car... I'll need a timing light too. Quote Link to comment
mike Posted October 3, 2009 Report Share Posted October 3, 2009 (edited) check/replace all your vacuum lines, check to make sure that your intake/exhaust manifolds are tight (think snug... dont overtighten!!!! check FSM for torque #s) make sure your carb is bolted down tight (snug again) and check your points, replace if bad... Also pull the distributor cap, unhook the vac advance hose from the base of your carb and suck on the end of it while watching your points, if nothing moves your vac advance is shot. If it hasnt been messed with and was running like a top dont mess with the adjustments of the carb until you check the rest of the stuff. My guess would be points are starting to crap out... Cheap fix... You probably got it pretty warm on your drive and if its been an around town truck with no long distance freeway driving for a while its entirely likely that something small went bad... If its stock, you dont have a coolant overflow tank so check your coolant level too. As far as brakes, it sounds like your booster might be bad or maybe you have a leak in the big vacuum line somewhere... if that is brakefluid, find where its coming from quick like. Good luck Edited October 3, 2009 by mike Quote Link to comment
slodat Posted October 3, 2009 Report Share Posted October 3, 2009 Does the fuel pump have screws holding the top and bottom half together or is it smooth on top with no screws into the bottom? The fuel pumps with the screws are MUCH better (and usually made in Japan) than the cheap ones with no screws. My money is on the fuel pump if it is dying out... I've had that happen on 3 different rigs. The diaphram gets a pinhole and is fine at lower engine speeds and loads and can't deliver enough fuel at high loads like a hill. There's an ebay seller that sells Nikki L series fuel pumps on ebay named JoeTLC. Last time I bought them it was about $15, which is a screaming deal. Shit, I think I've still got 2 or 3 in my parts stash.. Anyway, if the fuel filter and ignition are good, I'd check the fuel pump as I've described.. Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 check/replace all your vacuum lines, check to make sure that your intake/exhaust manifolds are tight (think snug... dont overtighten!!!! check FSM for torque #s) make sure your carb is bolted down tight (snug again) and check your points, replace if bad... Also pull the distributor cap, unhook the vac advance hose from the base of your carb and suck on the end of it while watching your points, if nothing moves your vac advance is shot. If it hasnt been messed with and was running like a top dont mess with the adjustments of the carb until you check the rest of the stuff. My guess would be points are starting to crap out... Cheap fix... You probably got it pretty warm on your drive and if its been an around town truck with no long distance freeway driving for a while its entirely likely that something small went bad... If its stock, you dont have a coolant overflow tank so check your coolant level too. As far as brakes, it sounds like your booster might be bad or maybe you have a leak in the big vacuum line somewhere... if that is brakefluid, find where its coming from quick like. Good luck Thanks, I will check this stuff tomorrow and I'll post an update with some pics. What I thought was brake fluid is actually oil coming from the spacer behind the fuel pump and getting blown towards the back of the engine compartment. The booster is brand new- the guy I bought it from had pretty much everything in the brake system replaced. He gave me all the receipts. He said that the brakes might need more adjustment- they don't feel responsive enough to me. Maybe they weren't bled properly? I've never bled brakes- it's just a guess. I checked the coolant and it looks a bit low. I took off the air filter and it definitely looks like some stuff has been jerry-rigged on the carb. Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 Does the fuel pump have screws holding the top and bottom half together or is it smooth on top with no screws into the bottom? The fuel pumps with the screws are MUCH better (and usually made in Japan) than the cheap ones with no screws. My money is on the fuel pump if it is dying out... I've had that happen on 3 different rigs. The diaphram gets a pinhole and is fine at lower engine speeds and loads and can't deliver enough fuel at high loads like a hill. There's an ebay seller that sells Nikki L series fuel pumps on ebay named JoeTLC. Last time I bought them it was about $15, which is a screaming deal. Shit, I think I've still got 2 or 3 in my parts stash.. Anyway, if the fuel filter and ignition are good, I'd check the fuel pump as I've described.. The one on my truck has screws but it looks pretty old. I'll check the vac advance, points, and some other stuff first, then I'll move on tho the fuel pump. I'll check out the ones on ebay and put one on my watch list. Thanks! Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 By popular demand here are some pics. Side pic. interior pic. I'll be posting some pics of the engine compartment with some comments and questions. Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 (edited) This is what my carb float looks like... appears to need an adjustment? The drawing in the 1974 shop manual PDF looks upside down compared to my float and I'm totally confused by this. I ordered a 1973 manual which should arrive in a few days. In the interim if anyone has input on adjusting the float please fire away. I checked the vac advance by sucking on the hose and it appears to be working... although I found a nice little piece of wood in the slot to keep the distributor cap aligned. What is the fix here? If I order a new cap with points and condenser will I need to order additional pieces to eliminate this wood piece? The wires are a total mess... I'm beginning to regret this purchase... Some rigged hose that was stuffed inside a bigger hose. I pasted 2 pics together to show both ends... it originates from a line that comes up the firewall below the master cylinder into a brass thing that is zip-tied... it then goes into the larger hose which goes somewhere between the carb and the exhaust manifold... wtf is this? some thing that appears to be held in place with 2 bolts... totally blocked off... this needs to go... I'm exempt from smogging laws with a 1973 here in California... my guess is it's part of the old emissions system. Another wonky thing that is bloked off... unless someone here starts screaming that it needs to be hooked up to something I'm going to eliminate it with a threaded plug. Edited October 3, 2009 by SHIFT Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 I'll have to hitch a ride into town to get stuff... I live in the mountains and I can't drive this thing the way it keeps bogging out and misfiring on the hills... I'm going to pick up a set of tools and some parts/supplies like vac hoses, ignition wires, distributor cap, points, condenser, and generally stuff I will need to get the truck running right. I suppose I'll need a timing light and I'll have to learn how to use it... I'm making a list... can anyone think of anything I should pick up while I'm in town? like I just thought of a feeler gauge to adjust the points? My priority is to get the truck running reliably because I need basic transportation right now... I'm sure I'll fix the truck up a bit further in the near future. Quote Link to comment
datzenmike Posted October 3, 2009 Report Share Posted October 3, 2009 (edited) Correct fuel level should be at the horizontal line on the glass. Below: Looks like you have an L18 (or L18 components on your engine) Some #%@*$ previous owner has removed the EGR manifold that bolts to the side of the intake below the carb and screwed it up. I hate when people do this and make a mess while thinking this is an improvement!!! The worst thing is the loss of the PCV valve... probably the larger hose (with the small one inside) is the engine vent hose from the side of the block behind the manifolds. Without the PCV valve there is no where to connect it.... idiots! Above Also in this picture, look just below the glass in the front of the carb and slightly to the left.... you can see a hex bolt. Likely it's gear clamped to a hose to cap off the coolant line from the intake manifold. It should instead have a hose going to a T fitting which joins to this, below: ... and then continue down and across the front of the motor to the lower radiator hose inlet to the block and connected there. Coolant should circulate from the head through the intake out of the intake and join with coolant from the thermostat housing and then down to the lower rad inlet and back to the motor. The warming effect on the intake makes the motor run smoother in all weather. Water circulated past the thermostat allows it to open at the proper temp. With yours disconnected the engine will run hot before it opens. BRAKES. You have a vacuum booster to help reduce peddle effort. To test it, shut motor off and pump brakes several times to release any residual vacuum and hold down gently. Start motor and the peddle should drop down slightly as the vacuum builds. Edited October 3, 2009 by datzenmike Quote Link to comment
nukeday Posted October 3, 2009 Report Share Posted October 3, 2009 Just so you know...datzenmike knows just about everything about pretty much every Datsun model in North America. A manual for the 620 would be a good thing, but I know how money can be tight sometimes. Here's a quick tutorial on float adjustment. Use this at your own risk, if you screw the float up, you'll probably have a dead carb. Be careful, go slowly and LOOK at what you're working with before you start removing and bending stuff. This is a trial and error process, so be very careful of the bowl gasket, don't overtighten the 3 screws on the front or you'll bend the plate and it will leak like crazy. I want to say you'll need to bend the float down a smidge in this case. My experience has been that with the fuel at the line in the glass, the carb will run too rich. I like about 1/16" to 1/4" below the line. I'm at a fairly low elevation, maybe you'll do better with it right at the line. Make sure the truck is off, preferably with the keys in your pocket. When you loosen the 3 captive screws, fuel will drip/pour out of the bottom of the carb where the glass meets the carb. It's supposed to do that, when you put it back together, crank the engine a few times to refill the fuel bowl before you actually try to start it. Here you go, have fun: Reassembly is just the reverse of these steps. Make sure the truck is cool when you do this as the fuel in the bowl will pour right out onto the exhaust manifold. Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 (edited) Correct fuel level should be at the horizontal line on the glass. Below: Looks like you have an L18 (or L18 components on your engine) Some #%@*$ previous owner has removed the EGR manifold that bolts to the side of the intake below the carb and screwed it up. I hate when people do this and make a mess while thinking this is an improvement!!! The worst thing is the loss of the PCV valve... probably the larger hose (with the small one inside) is the engine vent hose from the side of the block behind the manifolds. Without the PCV valve there is no where to connect it.... idiots! Above Also in this picture, look just below the glass in the front of the carb and slightly to the left.... you can see a hex bolt. Likely it's gear clamped to a hose to cap off the coolant line from the intake manifold. It should instead have a hose going to a T fitting which joins to this, below: ... and then continue down and across the front of the motor to the lower radiator hose inlet to the block and connected there. Coolant should circulate from the head through the intake out of the intake and join with coolant from the thermostat housing and then down to the lower rad inlet and back to the motor. The warming effect on the intake makes the motor run smoother in all weather. Water circulated past the thermostat allows it to open at the proper temp. With yours disconnected the engine will run hot before it opens. BRAKES. You have a vacuum booster to help reduce peddle effort. To test it, shut motor off and pump brakes several times to release any residual vacuum and hold down gently. Start motor and the peddle should drop down slightly as the vacuum builds. Wow, that is some very informative stuff. I have more questions now though... 1- How do I get the fuel up to the horizontal line on the glass? I see a pic was just posted on this- Thanks! 2- I will buy a PCV valve (but I'm not clear where it goes), then connect it to the engine vent? is this correct? Any idea what the smaller hose is that is stuffed inside the engine vent hose? Should this hose stay connected to the engine vent hose as well with a "T" fitting? 3- The thing you thought was a hex bolt in a gear-clamped hose is actually a threaded plug. Maybe it's the similar one capped off on the right that gets connected to the thermostat housing? (see pic below) Also, how do I hook it into the lower rad hose inlet? with another "T" fitting? what is this nasty looking thing that is screwed into the piece that is bolted to the side of the intake with 2 blocked off vac hose fittings behind it? I peeled back some old tape and it looks to have been wired to something. Edited October 3, 2009 by SHIFT Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 Sorry for all the questions but I have a manual being shipped and I won't have it for at least a few days. I'll look at the 74 manual again to see if I can figure out the hoses and PCV valve stuff. Quote Link to comment
SHIFT Posted October 3, 2009 Author Report Share Posted October 3, 2009 I'm starting to make some sense from the drawings in 74 PDF manual. Thanks for all of the input guys. I figured out what the wire-tied brass thing is on the end of the thinner hose that is stuffed inside the block vent hose... its a flow guide valve... now I have to figure out what hoses and fittings to buy. This is nuts... I'm going to try adjusting the float now. Quote Link to comment
datzenmike Posted October 4, 2009 Report Share Posted October 4, 2009 (edited) Here is a shot of the intake coolant outlet fitting. Yours was likely removed and a bolt threaded in to seal it. http://i138.photobucket.com/albums/q251/datzenmike/620intake001Large.jpg[/img]"] Here is a shot of one of the intake runner inlet ports. Water flows from the head along the under side of the runner to the carb base and out the fitting as described. http://i138.photobucket.com/albums/q251/datzenmike/620intake002Large.jpg[/img]"] Above. OK now I can see that this is a solenoid, so this IS an L16 (not L18). This solenoid is switched off below 10 MPH by the speedometer to vent the BCDD. The hose is off the BCDD unit so this won't affect running so for now just leave it as is. The flow guide only allows fumes from the carb into the PCV system. It will run without it for now. If you look below behind the exhaust manifold you will see a 1" metal tube sticking out of the block with a small metal tube on it for a connection to the flow guide like this: http://i138.photobucket.com/albums/q251/datzenmike/L%20Z%20Heads%20and%20Motors/L16blockpcv.jpg[/img]"]. The large pipe should have a large rubber hose going up to the PCV valve screwed into the intake below the carb. Just so you know...datzenmike knows just about everything about pretty much every Datsun model in North America. Thanks, but that is SO untrue. :lol: Edited October 4, 2009 by datzenmike Quote Link to comment
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