Usually you will see mixing of water and oil, but you can do a pressure test on the cooling system, there are also test strips available for checking for coolant in the exhuast, a oil sample will give you good info as well
1990 F350 7.3 n/a overheating
- Thread starter zaroot
- Start date
The_Josh_Bear
Full Access Member
Oh yeah 1500 miles it should certainly be burped out!
Dang. Not sure on the HG test, others with more expertise will chime in soon I am sure.
Dang. Not sure on the HG test, others with more expertise will chime in soon I am sure.
G. Mann
Full Access Member
Just read through the thread... didn't see where you pressure checked the radiator cap, or pressure checked the radiator while engine was at operation temp [typical test tool has a do-dad that fits the radiator cap opening with a pressure gage on top that reads pressure in your coolant system.
If you have a head gasket leaking, combustion chamber pressure is way higher than coolant pressure, if the head gasket leak is into the cooling passages.. It's also much hotter, so will cause overheat/overload of the cooling system...
Pretty simple and quick test... might help you make good decisions about if you need to pull heads, or not.
If you have a head gasket leaking, combustion chamber pressure is way higher than coolant pressure, if the head gasket leak is into the cooling passages.. It's also much hotter, so will cause overheat/overload of the cooling system...
Pretty simple and quick test... might help you make good decisions about if you need to pull heads, or not.
zaroot
Registered User
I will look into the tester cap, good idea. The pressure being much higher in compression chamber than cooling system is why I think I have no oil/coolant contamination. The high pressure gases are seeing into the cooling system, causing the pressure @ cold/startup, and causing the high engine coolant temps at load or at speed. I do not think it is an air flow problem; but did clean the bimetal coil really well, and will be adding a little silicone fluid to the clutch.
Thanks for all the insight!
Thanks for all the insight!
Don't put any significance in the fact that it is overheating at highway speed. Mine did the same thing, acting the same way as yours is, and it would also overheat as I was going down the highway. The temperature gauge on mine acted like it was connected to the throttle. More throttle, it would move up, less throttle, it would go down. Of course pulling a load means more throttle, so it would go up faster.
Many parts later I fixed mine, it was the clutch fan. Instead of buying a new clutch I just locked it together with some brackets. Now during the hottest days of the month, pulling up any hill, it does not overheat. It will start getting hot if I am lugging it a little too much with a load, so I move the transmission into a lower gear, and with it still floored but running higher rpms, the temp comes right down.
Many parts later I fixed mine, it was the clutch fan. Instead of buying a new clutch I just locked it together with some brackets. Now during the hottest days of the month, pulling up any hill, it does not overheat. It will start getting hot if I am lugging it a little too much with a load, so I move the transmission into a lower gear, and with it still floored but running higher rpms, the temp comes right down.
Get the radiator "rodded". Should be able to find a radiator shop that works on big truck radiators to do the job. Will probably have to pull it yourself and take it to them. They remove the top and bottom of the radiator and then scrape out the tubes. The only way to make sure it is clean.
I went thru all the parts, but the truck was still getting hot. Looking inside the neck, the radiator looked fine. Getting it rodded significantly lowered the operating temperature. I had replaced the fan clutch but could never hear it kick in until I got the radiator cleaned. Now I hear it kick in only on the interstate with the AC on max. It was pretty much locked on all the time before- why i never noticed it kicking in. This is a must-do on all older vehicles
I went thru all the parts, but the truck was still getting hot. Looking inside the neck, the radiator looked fine. Getting it rodded significantly lowered the operating temperature. I had replaced the fan clutch but could never hear it kick in until I got the radiator cleaned. Now I hear it kick in only on the interstate with the AC on max. It was pretty much locked on all the time before- why i never noticed it kicking in. This is a must-do on all older vehicles
You can not rod an IDI radiator due to the dimpled tube design. If it’s in impeccable shape, a boil out may help,but if’s it’s in sad shape, unfortunately the best/most cost effective oprion is to replace the radiator.
Not all IDIs! Rodding totally fixed the overheating problem in my stock 1994 7.3 NA IDI
zaroot
Registered User
As suspected, I think the HG is blown. From cold start, within about 30 sec, it was up to 10psi. The highest it got at 190-191F idling was 27psi. Safe to safe my cooling system was pressuring and causing my ECT spikes while towing and freeway driving.
I did remove the fan clutch to inspect, and do the silicone fluid mod. Upon drilling a hole into the hub pocket, not a drop of existing fluid was in there. I am going to degrease the back area and reseal with black RTV. Will put about 35cc of 6000 CSE fluid into the clutch and see how she does.
She hung in there on stock HGs until 180k. Not thrilled, but not disappointed. Going to try and nurse along while I collect 12v swap parts. If I doing a HG, it’s gonna be one instead of two, on an engine sitting here on the ground. Thanks to everyone’s insight.
I did remove the fan clutch to inspect, and do the silicone fluid mod. Upon drilling a hole into the hub pocket, not a drop of existing fluid was in there. I am going to degrease the back area and reseal with black RTV. Will put about 35cc of 6000 CSE fluid into the clutch and see how she does.
She hung in there on stock HGs until 180k. Not thrilled, but not disappointed. Going to try and nurse along while I collect 12v swap parts. If I doing a HG, it’s gonna be one instead of two, on an engine sitting here on the ground. Thanks to everyone’s insight.
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Glad you tracked it down, that’s a wicked amount of coolant pressure. Peculiar to see no liquids mixing but sounds like you found the cause non the less
Get a 7psi rad cap. Is what I use. That High pressure can be ******* the rad with 13 psi cap
G. Mann
Full Access Member
I've always found the pressure gauge on the radiator to be quickest diagnosis for leaking head gaskets.
Looks like it's worked for you also. If it's turbo'ed, pull both heads and use studs. You'll go for more years than the Cummins conversion costs.
Looks like it's worked for you also. If it's turbo'ed, pull both heads and use studs. You'll go for more years than the Cummins conversion costs.
zaroot
Registered User
Unfortunately it is not currently a turbo setup. I looked into this extensively, scouting all the forums/CL/FB/eBay. About the cheapest I’ve seen shipped is $1000-1100 for old parts. I also have never spotted one in the junkyards around me, as they’re always N/A.
Figure $1200 for a used turbo kit, $200 to freshen it up with gaskets/seals/bolts/misc., new gaskets/studs/CDR for 7.3 @ $800-900, replacement of my tired Injectors and IP for $900-1000, and then an engine pull/reinstall, that’s a good chunk of change. Truck will also need a clutch soon, so that pushes me even further towards the swap.
I have a lead on a local running condition 12v VE pump engine, complete for $1200. Put $250 gasket kit, $440 for ARP studs, $125 for rocker machining, and the $3600 DCS complete kit puts me around $5600 + $500 contingency, so only 2x the cost to rebuild the ford.
Truck has new tires, new CM flatbed, new brakes and freshened d60kp front, it’s a crew cab in pretty good condition, will plan on keeping for a long time with a 12v.
Lastly, it will make hp/tq the IDI could not easily achieve, all while getting 3-4mpg better at all times.
If I could get an IDI turbo kit in usable condition for under $1000, I’d probably do it.
Change my mind? I’m always open to pointers and suggestions. Thanks!
Dirtleg
Full Access Member
My .02. 180k isn't too much mileage. My guess you originally damaged the head gasket when your water pump failed. Didn't become an issue till you stressed it with a load. You've basically found zero silicone in the fan clutch so there's a potential issue with cooling right there. Yes you've got a leak based on cooling system pressure. But having the heads off gives you an opportunity to open up the coolant passages that are blocked on the 7.3 and make it better than it was even at its best.
Cummins swap is a lot of time and $$$. Used engine may be great maybe not great. How much life left in the VE pump? Everything sounds great when someone's selling it to you.
Sounds like at the moment you could pull it, swap gaskets, stud it, fan clutch and normal clutch and stick it back in. Then get it timed properly for significantly less than the Cummins swap. At that point you're safe to find a turbo setup in your price range on your own schedule and you could do the IP and injectors at the same time as the turbo matching your fuel requirements to the turbo you select. At that point you've got an improved top end and all new intake and fuel system making significantly more power for certainly less dollars than the Cummins swap with used, unknown components.
But you just may be a Cummins guy and if that's the case go that route.
Cummins swap is a lot of time and $$$. Used engine may be great maybe not great. How much life left in the VE pump? Everything sounds great when someone's selling it to you.
Sounds like at the moment you could pull it, swap gaskets, stud it, fan clutch and normal clutch and stick it back in. Then get it timed properly for significantly less than the Cummins swap. At that point you're safe to find a turbo setup in your price range on your own schedule and you could do the IP and injectors at the same time as the turbo matching your fuel requirements to the turbo you select. At that point you've got an improved top end and all new intake and fuel system making significantly more power for certainly less dollars than the Cummins swap with used, unknown components.
But you just may be a Cummins guy and if that's the case go that route.
G. Mann
Full Access Member
What dirtleg said... X2 .... Cost of cummins conversion will buy a boat load of fuel... plus down time to do conversion...
Pull the engine, do the head gaskets, studs, seal it up, install new clutch... it all goes back just like it came out... couple days, you are back in business...
I agree with what was posted above, likely over heated and blew gasket when pump failed, it's just now catching up with you, or rather sneaking up on you, because the gasket isn't yet completely blown out.
Pull the engine, do the head gaskets, studs, seal it up, install new clutch... it all goes back just like it came out... couple days, you are back in business...
I agree with what was posted above, likely over heated and blew gasket when pump failed, it's just now catching up with you, or rather sneaking up on you, because the gasket isn't yet completely blown out.
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