wtnhunt Posted October 9, 2011 Report Share Posted October 9, 2011 Got a problem with coolant leaking from our 98 3/4 ton hd truck. It is a chevy 4wd and has a 350 and has 165,000+ miles on it. First thought when I found it was leaking was the water pump. Tough to see where it is leaking from though. There is coolant on the passenger side back of the bottom side of the block, not directly below the heater core. Checked to see if there was any moisture on the firewall below the heater core lines and they are fine. It is dripping and has moisture along the back of the oil pan. No idea where its leaking from, should not be anything back there to leak. Oil looks like it is fine. Also a leak at the front driver side of the engine, looks like that one could be coming from the water pump, but I cannot see whether it is or isn't. Not enough room to get my big hands in below the water pump to feel for leaks. Did not take the fan off YET, guessing I am going to have to to pinpoint the leak? Is it possible the water pump is causing both leaks and water channeling down the oil pan and dripping in the back? Quote Link to comment Share on other sites More sharing options...
elkoholic Posted October 9, 2011 Report Share Posted October 9, 2011 It is very probable that the water pump is the sole culprit and that is an easy to replace part on a chevy 350. You may also have a leaky freeze out plug. Replacement of a freeze out plug (really a casting plug) can be a bear of a job depending on location, especially if it is one on the back of the block and you have to pull the transmission. Hopefully, it is just the water pump. The best way to tell is pressure test the system, but you need the proper tool. Or, there is the old fashion way and just let it run and keep watch for the leak. You could always throw in some stop leak additive and hope for the best. I've known people whose whole cooling system was held together with radiator sealant. Good luck! Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 9, 2011 Author Report Share Posted October 9, 2011 Both leaks go from a drip drip with the engine off to a pretty heavy stream with the engine running and looks like they are leaking about equally while under pressure. Unfortunately I cannot see the underside of the water pump, did not feel any moisture on the passenger side of the pump, there are no apparent leaks from the top side. Quote Link to comment Share on other sites More sharing options...
LETMGROW Posted October 10, 2011 Report Share Posted October 10, 2011 Ah-Ha! The old intake manifold leak on this one. Common. To be sure, have a pressure test done. May have to do a little cleaning first, but I am almost sure this is the problem. 3 hr. job, intake gasket set, rocker cover gasket set, tbi gasket, good time to change the thermostat, by- pass hose, oil and filter. Chances are you will also need that pesky heater hose to manifold fitting and some heater hose. Don't let this go too long. IF it is the int. gasket, it may be leaking externally now but if it is let go too long it will leak internally causing serious engine damage. Coolant and oil don't mix. Distributor has to come out. I'll bet you will need a cap and rotor if they aren't fairly new. When the distributor is reinstalled it will have to be synchronized to the crank sensor. Lynn Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 10, 2011 Author Report Share Posted October 10, 2011 Thanks Lynn. Gonna see about getting it to a mechanic to pressure test. With the way it is leaking, don't want to drive it too far. Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 10, 2011 Author Report Share Posted October 10, 2011 Ah-Ha! The old intake manifold leak on this one. Common. To be sure, have a pressure test done. May have to do a little cleaning first, but I am almost sure this is the problem. 3 hr. job, intake gasket set, rocker cover gasket set, tbi gasket, good time to change the thermostat, by- pass hose, oil and filter. Chances are you will also need that pesky heater hose to manifold fitting and some heater hose. Don't let this go too long. IF it is the int. gasket, it may be leaking externally now but if it is let go too long it will leak internally causing serious engine damage. Coolant and oil don't mix. Distributor has to come out. I'll bet you will need a cap and rotor if they aren't fairly new. When the distributor is reinstalled it will have to be synchronized to the crank sensor. Lynn Most of that on the list there I have done before at one time or another, only thing that I would be worried about would be getting the distributor back right. Seems when we(my stepdad and I) pulled a few distributors way back we marked them and put them back aligned with the marks, honestly do not remember that was back in the 80's and those would have been 70's model vehicles. Your mention of 3 hours makes me laugh a little. Maybe 3 hours for you, but guessing that would be at least an all day or possibly even a weekend job for me. Definitely think I would start by giving everything a good cleaning before ever turning a wrench. The cap and rotor were replaced probably about 30,000 miles ago when I replaced the wires. The plastic manifold nipple has been replaced with a fitting, that was not a fun job getting that out but it was done quite a while back. Thermostat is original, will replace it. I am a bit concerned about the potential damage though. Wife had been driving the truck since she drives less mileage, I had no idea it was leaking as bad as it is and not really sure when it started. That said, the oil does look fine though and it is at the level it should be at, it was changed probably a month ago. If there were water in the oil it should be noticeable on the dipstick, shouldn't it? Quote Link to comment Share on other sites More sharing options...
92xj Posted October 10, 2011 Report Share Posted October 10, 2011 William, Yes water will be noticeable on the dipstick, it will look like chocolate milk with air bubbles in it and the level will be a lot higher than normal. Also, call the mechanic first and ask how much he will charge to pressure check the cooling system. Its an easy thing to do with very little labor time but some people like to charge 60 bucks to do it. When I would do them at our shop, we would do them for free but some charge. If he charges, go get the pressure tester from a parts store for 50 bucks and do it yourself. Quote Link to comment Share on other sites More sharing options...
LETMGROW Posted October 10, 2011 Report Share Posted October 10, 2011 (edited) The newer coolant is harder to detect than the old green stuff. If the oil level hasn't risen you are probably OK. Allright, 4 hours-tops. LOL The distributor has to be synchronized with a scan tool. Marking it before removal is the best way to get it back in close. I always turn the engine over so the rotor points straight forward before pulling it. Just my personal preference. Most Chev. have a mark on the manifold and dist. housing at the rear. You should be able to see this with a compact mirror. DO NOT put any silicone or other sealer on the gasket or gasket surfaces. These are designed to be installed dry. The mating ends however do require silicone to make a gasket. ( area between the block and manifold ) Lynn Edited October 10, 2011 by LETMGROW Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 10, 2011 Author Report Share Posted October 10, 2011 Thanks for the help here. William, Yes water will be noticeable on the dipstick, it will look like chocolate milk with air bubbles in it and the level will be a lot higher than normal. Also, call the mechanic first and ask how much he will charge to pressure check the cooling system. Its an easy thing to do with very little labor time but some people like to charge 60 bucks to do it. When I would do them at our shop, we would do them for free but some charge. If he charges, go get the pressure tester from a parts store for 50 bucks and do it yourself. Always heard it would look milky. Definitely not chocolate milky and no bubbles. I may actually have a pressure tester, gonna have to dig through the tools. Brought a lot of stuff home from my mothers house after my stepdad passed away and to be honest not really sure anymore what I do and don't have. The newer coolant is harder to detect than the old green stuff. If the oil level hasn't risen you are probably OK. Allright, 4 hours-tops. LOL The distributor has to be synchronized with a scan tool. Marking it before removal is the best way to get it back in close. I always turn the engine over so the rotor points straight forward before pulling it. Just my personal preference. Most Chev. have a mark on the manifold and dist. housing at the rear. You should be able to see this with a compact mirror. DO NOT put any silicone or other sealer on the gasket or gasket surfaces. These are designed to be installed dry. The mating ends however do require silicone to make a gasket. ( area between the block and manifold ) Lynn Glad you said that on the silicone, I would have ended up using it had I not seen this. Far as the scan, say if I got it close, would it be driveable to get it to a person to have it scanned, or maybe a parts store would loan/rent one out? Also on the coolant, I know chevy uses dex cool and I have to admit here that I used the wal mart "mix with any color or brand", which is yellow green, mistake? Quote Link to comment Share on other sites More sharing options...
Shaun_300 Posted October 11, 2011 Report Share Posted October 11, 2011 Yeah the intake manifold gaskets are pretty common on the ole 350's. Fairly easy to change, biggest pain of the whole job is the distributor lining up. I always mark it in 2 places to be sure, tip of rotor to distributor and base to the intake manifold. Waterpumps are also pretty common too, definitely want to get it pressure tested before replacing the intake gaskets. Also if you do change the intake gaskets take a good look at the distributor gear itself, they were pretty common for wearing so it may be due to replace if you haven't had to change it already, they're pretty cheap. Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 12, 2011 Author Report Share Posted October 12, 2011 Don't think I have a coolant system pressure tester, thought I had seen one at some point, but have not found it yet. Have a compression gauge, but that is not gonna do me any good with this. With possibly having to pay to have the system pressure tested, or buying a kit for $50-75 and then possibly running into distributor problems and possibly having to pay someone to scan that, wondering if I would not be best off to just see about paying someone and not worrying with it. I mean if Lynn says 3-4 hours tops on the job, how much labor am I gonna be looking at for a shop? Tried calling the mechanic I would use to see about a pressure test but have been unable to get a hold of him yet. Quote Link to comment Share on other sites More sharing options...
LETMGROW Posted October 12, 2011 Report Share Posted October 12, 2011 Mitchell publishes the flat rate time for the manifold R&R and gasket change at 4.8 hours. Warranty rate 2.9 hr. This can vary of course with additional labor time necessary to do extra cleaning, broken bolts, hose changes etc. The 4.8 hr. time is for a truck with A/C. We unbolt the compressor and flip it over onto a fender cover on the right side. We do not discharge the A/C system. Multiply this time estimate by the shop's hourly rate and you should be in the " ballpark " Add 100 - 125 $ for gaskets and misc parts. If we do the job we waive charges for the pressure testing. Lynn Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 13, 2011 Author Report Share Posted October 13, 2011 Mitchell publishes the flat rate time for the manifold R&R and gasket change at 4.8 hours. Warranty rate 2.9 hr. This can vary of course with additional labor time necessary to do extra cleaning, broken bolts, hose changes etc. The 4.8 hr. time is for a truck with A/C. We unbolt the compressor and flip it over onto a fender cover on the right side. We do not discharge the A/C system. Multiply this time estimate by the shop's hourly rate and you should be in the " ballpark " Add 100 - 125 $ for gaskets and misc parts. If we do the job we waive charges for the pressure testing. Lynn Got a hold of the mechanic this morning and he said probably looking at $250 parts and all. Thinking by the time I buy a tester and gaskets and potential problems getting the distributor back right that I may be better off to just have him take care of it. Quote Link to comment Share on other sites More sharing options...
LETMGROW Posted October 13, 2011 Report Share Posted October 13, 2011 Sounds awful cheap to me. However, if you trust him, go for it. Keep us posted on your results. Lynn Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 13, 2011 Author Report Share Posted October 13, 2011 Sounds awful cheap to me. However, if you trust him, go for it. Keep us posted on your results. Lynn We'll see, probably gonna drop it off this afternoon. Really hoping there is nothing more wrong. Dunno about being too cheap Lynn, imagine rates there are considerably higher due to costs of living. If it takes him between 3-4 hours and parts run him $100 he is looking at around $40 an hour before his overhead. Far as I know in this area this is probably one of the better mechanics around. I have had him do a little work for me before and had no problems. Quote Link to comment Share on other sites More sharing options...
Shaun_300 Posted October 13, 2011 Report Share Posted October 13, 2011 Think you're doing the right thing William. That heater hose fitting is a real PITA if it breaks off too. That sounds like one heck of a deal. It'd be around $600 to do it at the dealer I work at. Our labor rate is $99/hour. Quote Link to comment Share on other sites More sharing options...
LETMGROW Posted October 13, 2011 Report Share Posted October 13, 2011 Perhaps I could have been a little more specific on how we perform these jobs. After we determine with a pressure test the int. gasket is bad, we remove the manifold, clean gasket mating surfaces, remove the upper plenum and injectors. After stripping the manifold we put it into a hot water/ acid spray cabinet and give it a thorough cleaning. The upper plenum is cleaned by hand with mineral spirits. The plenum is plastic and wouldn't hold up to the spray acid. Rocker covers are cleaned and go into the spray cabinet along with the housing for the thermostat. The area between the manifold and plenum gets nasty dirty. Failure to do these extra steps is not acceptable to our shop standards. This is one reason I pay my people by the hour. If we take a little longer to do the job right, so be it. Incidently, the rocker covers must come off as they lap over the manifold enough to block the manifold removal. While I may have said 4 hours to do this job, that is actual average time it would probably take us. Bear in mind I have one technician who has done at least a couple dozen of these jobs. He knows the little tricks quite well. BTW our labor rate currently is $65 per hour usually figured on published flat times. A minimum of parts we would use: Manifold gasket kit $ 48.44 This kit includesupper plenum gasket and necessary seals to complete the normal job. Rocker cover gaskets $ 30.58 Thermostat $ 11.32 Oil filter $ 5.00 by-pass hose $9.79 Anti freeze $ 28.00 oil $ 20.00 Parts $ 133.13 You still may need a belt, distributor gear, cap and or rotor. You would have these off anyway, why not replace now if questionable. Labor would be: 318.50 Parts 133.13 Total 451.63 Parts prices are NAPA list. Most shops will discount these somewhat. Lynn Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 14, 2011 Author Report Share Posted October 14, 2011 That heater hose fitting is a real PITA if it breaks off too. I fixed that quite a few years back Shaun, yep a pita for sure. Have done 2 of those actually, had to replace the one on our yukon too. Perhaps I could have been a little more specific on how we perform these jobs...... While I may have said 4 hours to do this job, that is actual average time it would probably take us. Bear in mind I have one technician who has done at least a couple dozen of these jobs. He knows the little tricks quite well. Thanks Lynn. Appreciate your insight. Quote Link to comment Share on other sites More sharing options...
LETMGROW Posted October 17, 2011 Report Share Posted October 17, 2011 We're all waiting to hear how you made out? Lynn Quote Link to comment Share on other sites More sharing options...
wtnhunt Posted October 17, 2011 Author Report Share Posted October 17, 2011 We're all waiting to hear how you made out? Lynn Got the truck back this afternoon, he ran a bit behind, he stays pretty busy. Was the intake manifold gasket, great assessment Lynn. I have not driven it yet, but no leaks, radiator is full. He said those intake manifold gaskets were real common to leak, guessing he probably changed out a few over the years. Quote Link to comment Share on other sites More sharing options...
Shaun_300 Posted October 18, 2011 Report Share Posted October 18, 2011 Glad you got it fixed up William. Yes they were pretty common to leak on those engines. Quote Link to comment Share on other sites More sharing options...
LETMGROW Posted October 18, 2011 Report Share Posted October 18, 2011 Geez! We all get lucky once in a while. Glad it worked out for you. Lynn Quote Link to comment Share on other sites More sharing options...
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