5.3l LM4 overheating and blowing hoses
09-04-2012, 09:35 AM
#1
5.3l LM4 overheating and blowing hoses Hey everybody! I have an LM4 in my '95 Volvo 960 wagon. Ever since I've done the swap, I've always had lots of underhood temp issues. It'll often, intermittently, suddenly shoot up in temp and overheat and kick in thermal protection mode around 235*F (killing cylinders). My fan speeds are set to kick on at 201* low, and 204* high. I just installed a new t-stat yesterday to no avail. It's not a HG issue, and it's a fairly new radiator. Help? Is it simply an air pocket?
Temps will shoot up, at idle, while driving, doesn't matter. Fan can be on on high and the temps will still rise. It'll get so hot it'll build so much pressure that it'll pop hoses. I've blown 2 heater hoses & 3 steam tube hoses. Never an upper or lower radiator hose. FWIW, I installed a Saab 15 psi cap that is the same threads as my stock Volvo coolant bottle (stock volvo cap is 24 psi). I never hear any hissing or see any coolant spilling out of my cap. Could this simply be a case of a bad cap not venting to atmosphere like it should be? Would a 24psi cap damage anything on this engine if I were to go back to the stock Volvo cap, which I know works because it worked on the stock engine?
Temps will shoot up, at idle, while driving, doesn't matter. Fan can be on on high and the temps will still rise. It'll get so hot it'll build so much pressure that it'll pop hoses. I've blown 2 heater hoses & 3 steam tube hoses. Never an upper or lower radiator hose. FWIW, I installed a Saab 15 psi cap that is the same threads as my stock Volvo coolant bottle (stock volvo cap is 24 psi). I never hear any hissing or see any coolant spilling out of my cap. Could this simply be a case of a bad cap not venting to atmosphere like it should be? Would a 24psi cap damage anything on this engine if I were to go back to the stock Volvo cap, which I know works because it worked on the stock engine?
09-08-2012, 10:02 AM
#2
What condition is the radiator in? Also are you sure the fans are pulling/pushing the way they should be. I wouldn't run a 24psi cap, IMO it would only compound your problem probably blowing more stuff up.
Have the heads been off the engine? If so do you remember what head gaskets you used.
Have the heads been off the engine? If so do you remember what head gaskets you used.
09-08-2012, 06:58 PM
#3
What condition is the radiator in? Also are you sure the fans are pulling/pushing the way they should be. I wouldn't run a 24psi cap, IMO it would only compound your problem probably blowing more stuff up.
Have the heads been off the engine? If so do you remember what head gaskets you used.
Have the heads been off the engine? If so do you remember what head gaskets you used.
Radiator is about 2 years old, and fan is in the correct position - stock Volvo fan, etc. Motor has not been apart ans oilpan, and cam swap.
09-08-2012, 11:26 PM
#6
Stock Volvo fan is HUGE. Stock radiator is equally huge. More surface area than 'vette ones, I'd need to find the cfm rating of the stock fan, but it's up there.
Well, yes and no. Not right away, but it's like it'll be fine for awhile, and then all of a sudden temps skyrocket and it'll get hot enough to hit hi-temp limp mode (~235*Fish) and as soon as not long after that it gets enough pressure built up to pop a hose. So, very intermittent. I can't find any kind of trends as to when or why.
09-08-2012, 11:42 PM
#7
Stock Volvo fan is HUGE. Stock radiator is equally huge. More surface area than 'vette ones, I'd need to find the cfm rating of the stock fan, but it's up there.
Well, yes and no. Not right away, but it's like it'll be fine for awhile, and then all of a sudden temps skyrocket and it'll get hot enough to hit hi-temp limp mode (~235*Fish) and as soon as not long after that it gets enough pressure built up to pop a hose. So, very intermittent. I can't find any kind of trends as to when or why.
Well, yes and no. Not right away, but it's like it'll be fine for awhile, and then all of a sudden temps skyrocket and it'll get hot enough to hit hi-temp limp mode (~235*Fish) and as soon as not long after that it gets enough pressure built up to pop a hose. So, very intermittent. I can't find any kind of trends as to when or why.
The main reason temps "shoot" up quickly......stuck t-stat or a slow-to-open t-stat or a t-stat that only opens partially. Try another one. Those things come as duds all the time when they're new.
If it was a fan problem....temps would rise slowly...not fast.
Air bubble....causes temps to rise slowly and they will not stop rising. But you said you ran normal at some point.
.
Trending Topics
09-08-2012, 11:53 PM
#8
Remove the t-stat....put the housing back on, top off the coolant/water and go for a ride. Just a mellow ride cruising steady. See if it stays relatively cool.
The main reason temps "shoot" up quickly......stuck t-stat or a slow-to-open t-stat or a t-stat that only opens partially. Try another one. Those things come as duds all the time when they're new.
If it was a fan problem....temps would rise slowly...not fast.
Air bubble....causes temps to rise slowly and they will not stop rising. But you said you ran normal at some point.
.
The main reason temps "shoot" up quickly......stuck t-stat or a slow-to-open t-stat or a t-stat that only opens partially. Try another one. Those things come as duds all the time when they're new.
If it was a fan problem....temps would rise slowly...not fast.
Air bubble....causes temps to rise slowly and they will not stop rising. But you said you ran normal at some point.
.
Ya, something keeps telling me air bubble too. However, it's popped hoses so many times now (5 i think??) that it's been refilled a bunch, and honestly - it's very possible there is an air bubble. I'm going to re-route my steam tube hoses and take it directly to the radiator overflow nipple instead of T'ing into the upper radiator hose (never like that idea anyways). Also need to find a new cap I think, as I'm really not sure if this one is even opening up to bleed pressure at all.
After it popped the plug on the radiator a couple weeks ago, I repaired that, and replaced the t-stat with a new Stant unit from Advance. Drove around for probably 30 minutes, just cruising, got on it a bit, no big deal. Ran ~193-195 the whole time. As I started to get closer to home, it started creeping to 215-220. Sat there for a bit, and then it started going up more from there, which thankfully I got it home and shut it down at about 230. About 2 minutes after I shut it down, one of the steam tubes popped near the hose clamp at one of the connectors near the radiator.
09-09-2012, 12:16 AM
#9
Ya, something keeps telling me air bubble too. However, it's popped hoses so many times now (5 i think??) that it's been refilled a bunch, and honestly - it's very possible there is an air bubble. I'm going to re-route my steam tube hoses and take it directly to the radiator overflow nipple instead of T'ing into the upper radiator hose (never like that idea anyways). Also need to find a new cap I think, as I'm really not sure if this one is even opening up to bleed pressure at all.
After it popped the plug on the radiator a couple weeks ago, I repaired that, and replaced the t-stat with a new Stant unit from Advance. Drove around for probably 30 minutes, just cruising, got on it a bit, no big deal. Ran ~193-195 the whole time. As I started to get closer to home, it started creeping to 215-220. Sat there for a bit, and then it started going up more from there, which thankfully I got it home and shut it down at about 230. About 2 minutes after I shut it down, one of the steam tubes popped near the hose clamp at one of the connectors near the radiator.
After it popped the plug on the radiator a couple weeks ago, I repaired that, and replaced the t-stat with a new Stant unit from Advance. Drove around for probably 30 minutes, just cruising, got on it a bit, no big deal. Ran ~193-195 the whole time. As I started to get closer to home, it started creeping to 215-220. Sat there for a bit, and then it started going up more from there, which thankfully I got it home and shut it down at about 230. About 2 minutes after I shut it down, one of the steam tubes popped near the hose clamp at one of the connectors near the radiator.
I wonder if that 230*F is correct. Are you using a scanner to read the temps....or just the gauge in the cluster?
It has to get REALLY hot to blow hoses. My 427ci has seen the needle buried into the red 2-3 times....never blew a hose. It did nothing. Just cooled off and I drove off.....after putting a new serpentine back on.....lol
Drill a hole in the t-stat way up at the 12' o-clock position near the edge......that will let the air bubble by the t-stat as you top it off. Just a small hole maybe 1/8" diameter. It won't affect its normal operation.
Also, squeezing the upper and lower radiator hoses rapidly 30-40 times each, continually going back and forth, while the engine is warming up....will move the air bubble past the t-stat. Then when you see the coolant level drop down...you know the t-stat just opened. Top it off "immediately". If you do that, you will be 100% assured there is no air in the system. Put the radiator cap back on....go for a drive.
.
09-09-2012, 01:00 AM
#10
You shouldn't be blowing hoses....the pressure should blow out the radiator cap first. Get a new cap.....18psi if you can. That should at least stop hoses from popping.
I wonder if that 230*F is correct. Are you using a scanner to read the temps....or just the gauge in the cluster?
It has to get REALLY hot to blow hoses. My 427ci has seen the needle buried into the red 2-3 times....never blew a hose. It did nothing. Just cooled off and I drove off.....after putting a new serpentine back on.....lol
Drill a hole in the t-stat way up at the 12' o-clock position near the edge......that will let the air bubble by the t-stat as you top it off. Just a small hole maybe 1/8" diameter. It won't affect its normal operation.
Also, squeezing the upper and lower radiator hoses rapidly 30-40 times each, continually going back and forth, while the engine is warming up....will move the air bubble past the t-stat. Then when you see the coolant level drop down...you know the t-stat just opened. Top it off "immediately". If you do that, you will be 100% assured there is no air in the system. Put the radiator cap back on....go for a drive.
.
I wonder if that 230*F is correct. Are you using a scanner to read the temps....or just the gauge in the cluster?
It has to get REALLY hot to blow hoses. My 427ci has seen the needle buried into the red 2-3 times....never blew a hose. It did nothing. Just cooled off and I drove off.....after putting a new serpentine back on.....lol
Drill a hole in the t-stat way up at the 12' o-clock position near the edge......that will let the air bubble by the t-stat as you top it off. Just a small hole maybe 1/8" diameter. It won't affect its normal operation.
Also, squeezing the upper and lower radiator hoses rapidly 30-40 times each, continually going back and forth, while the engine is warming up....will move the air bubble past the t-stat. Then when you see the coolant level drop down...you know the t-stat just opened. Top it off "immediately". If you do that, you will be 100% assured there is no air in the system. Put the radiator cap back on....go for a drive.
.
The 230 is from Torque on my Android phone. I'd say ti's pretty accurate, as my fan speeds are set to come on at 201*F low/204*F high, and it's usually pretty accurate as to when they turn on, so I'd assume the 230 is as well. I can squeeze the upper hose, but not the lower - lower has a coil inside it.
09-12-2012, 02:11 PM
#11
Well, I re-plumbed the steam tubes. Ran the steam tube off the drivers side head directly to the hose going from the top of the radiator to the top of the coolant bottle. So far so good.
EDIT: Also, forgot to mention - when I got it back together and drove it, when I got home and parked it, maybe 10-15 minutes later, the upper hose was collapsed. I let it cool down and then removed the cap, and the hose expanded again to it's regular size. Should I have left it collapsed longer to make sure there were no leaks or anything?
EDIT: Also, forgot to mention - when I got it back together and drove it, when I got home and parked it, maybe 10-15 minutes later, the upper hose was collapsed. I let it cool down and then removed the cap, and the hose expanded again to it's regular size. Should I have left it collapsed longer to make sure there were no leaks or anything?
Last edited by kendogg; 09-12-2012 at 02:47 PM.
09-13-2012, 01:55 PM
#12
Well, I re-plumbed the steam tubes. Ran the steam tube off the drivers side head directly to the hose going from the top of the radiator to the top of the coolant bottle. So far so good.
EDIT: Also, forgot to mention - when I got it back together and drove it, when I got home and parked it, maybe 10-15 minutes later, the upper hose was collapsed. I let it cool down and then removed the cap, and the hose expanded again to it's regular size. Should I have left it collapsed longer to make sure there were no leaks or anything?
EDIT: Also, forgot to mention - when I got it back together and drove it, when I got home and parked it, maybe 10-15 minutes later, the upper hose was collapsed. I let it cool down and then removed the cap, and the hose expanded again to it's regular size. Should I have left it collapsed longer to make sure there were no leaks or anything?
Its possible while you were driving it, somewhere, coolant leaked out or was squirt out while under pressure....then sucked in air as it cooled allowing the hose to collapse.
There must be a place where coolant is leaking out, even if its just like a cup's worth.
.
